If you're standing outside the Vatican museums at 8:00 am on a summer morning, chances are the line to get in already wraps around the block. Catholic or not, the mysteries of the Vatican seem to hold an indescribable allure for visitors to Rome.

Vatican City is the smallest country in the world with a population of around only one thousand. Virtually everybody has heard of the Sistine Chapel and St Peter's Basilica, but most of the Vatican remains a puzzle to the rest of the world. It is the secrets of notoriously restricted areas like the Vatican Archives that keep people fascinated with the tiny Catholic state.

Authors like Dan Brown have added fuel to the fire by surrounding the Vatican with mystery. For the most part, these stories are purely fictional, but that doesn't change the fact that the Vatican is an enigma that most people are clambering to dissect for themselves.

With all of the restricted access in the Vatican it is possible that there are still areas unbeknownst to everyone outside of the Catholic elite. Consequently, this list is a work in progress. New sections are now being unveiled to the public with greater frequency, but here are twenty just to get you started. Plan and book your trip well in advance and make sure to allocate a whole day to the Vatican. You will need it! Some of these spots are lesser known gems along the Vatican Museums tour; some are unmissable spots to search for in the Basilica and a few are the most restricted areas of the Vatican. So, unless you plan on becoming a cardinal, good luck with seeing everything!

20 20. St Peter's Tomb

If there is one single existence for the Vatican today, it is this tomb. Oddly enough, there is still no surety that the first century tomb is indeed St Peter's. Regardless, the original basilica was purposely built over the burial place of the saint. When St Peter's Basilica was rebuilt during the Renaissance, it was constructed over the same space.

To see St Peter's Tomb in the Vatican Necropolis, visitors need to contact the excavations office in advance. The tomb is one of the Vatican's most sacred spots so you will need to dress appropriately. It might be a hundred degrees outside but you'll still need to have your knees and shoulders covered.

19 19. The Vatican Necropolis

St Peter's tomb isn't the only treasured tomb in the Vatican Necropolis. The Necropolis was excavated during the 1940s leading to the discovery of pagan and Christian tombs predating Constantine's original basilica. The famous Tomb of the Julii covered in mosaics is particularly fascinating.

Due to the delicate conditions of the Necropolis, only small groups are allowed to visit and the total number of visitors at one time are restricted. Many people either do not realise they can tour the Necropolis or do not even know of its existence until they visit. For those who are in on the secret, tickets are highly coveted!

18 18. The Vatican Grottoes

Separate to the Necropolis, the Grottoes are home to the tombs of many famous saints, popes and monarchs including the recently deceased Pope John Paul II. The tombs range from simple to elaborate and since they are located immediately under the Basilica, there really isn't a reason to skip it. It is well worth a visit.

Unlike the Necropolis, the Grottoes are easily accessible. There is no need to fight for an exclusive spot to visit though many visitors to the Basilica miss the Grottoes without even realising it. They are free to visit, open everyday and can be accessed from inside the Basilica.

17 17. The Cupola

The cupola, or the Basilica's mammoth dome, is an essential stop for anyone visiting Rome. If tombs and underground chambers are too morbid or claustrophobic for you, the dome is a great alternative to make your visit to the Basilica extra special.

The elaborate dome was designed by Michelangelo and copied throughout Europe. Sadly, he did not live to see it completed. It stands shockingly tall at over 130 meters. Hundreds of years later it still dwarfs some of the surrounding buildings. Unsurprisingly the dome provides spectacular views over Rome, that is, if you can survive the hike to the top! Rest assured, there is an elevator that takes visitors part of the way and the view is definitely worth it. Not to mention you'll have the perfect shot to add to your Instagram.

16 16. Michelangelo's Pieta

Another masterpiece by Michelangelo albeit much smaller than his monumental dome, this marble statue can get lost amongst the columns and chapels of the Basilica, but it is definitely worth the hunt. It is located in the Basilica's first chapel on the right upon entering.

Right from its creation at the turn of the fifteenth century the statue was lauded with admiration and won Michelangelo widespread acclaim. It is famed for being the only piece that Michelangelo ever signed and he supposedly spent more time perfecting it than any of his other sculptures. Evidently he was pleased with his work and justifiably so. The Pieta, carved from a block of Carrara marble, is one of the most beautiful sculptures from the Renaissance.

15 15. The Chair Of Saint Peter

Once a simple wooden chair, it has been renovated and decorated over the centuries to become the elaborate piece you see today. In fact, it is so heavily decorated and blends so well with the rest of the Basilica that spotting it can be like playing a game of Where's Waldo? The chair currently sits at the back of the Basilica.

Traditional belief holds the chair belonged to St Peter though this is unlikely. Regardless, the chair holds a place of great importance in the Catholic Church and even has its own feast day dedicated to it. It might not be two thousand years old, but it is still astonishingly ancient and remains a testament to the endurance of the Catholic Church.

14 14. The Holy Door

This beautiful treasure's significance is not known widely to those outside of the Catholic Church. The door is one of the entrances to the Basilica and is intricately decorated with scenes in gold. However, with all of the opulent gold ornamentation in the Basilica, you could easily miss it. After all, so far it just sounds like a heavily adorned door, right?

Here is the catch, it is only opened by the Pope on jubilee years which do not come around very often. If you planned on just sneaking through you will be sadly disappointed. The doors are walled up from the inside so that they are unable to be opened. For the lucky people who were in Rome in 2015, Pope Francis broke with tradition and opened the doors for a special Extraordinary Jubilee of Mercy but do not count on this happening again anytime soon!

13 13. The Altar Of The Crucifixion Of St Peter

There seems to be countless beautiful altars in St Peter's Basilica but the Altar of the Crucifixion of St Peter is particularly special. Why? The Altar is supposedly in the exact spot where St Peter was executed in the Circus of Nero. Of course there is no way to verify this but it certainly makes for a great story.

The altarpiece has changed several times over the centuries. Now, a mosaic based on Guido Reni's 'Crucifixion of St Peter' sits above the altar. In a unique twist, St Peter is depicted being crucified upside down. The original painting hangs in the Vatican galleries.

12 12. The Sacristy And The Treasury

In the eighteenth century an octagonal sacristy was added to the Basilica. Interestingly, eight columns were taken from Hadrian's Villa in Tivoli to be used in the sacristy. They are quite possibly the oldest part of the Basilica.

However, the real priceless pieces lie in the treasury. Of course the Vatican could not have just one or two rooms to house their precious articles. Instead, they built ten. Together the rooms house some of the Catholic Church's most invaluable relics. Chief among them is the Vatican Cross which is encrusted with precious stones and perhaps more importantly, supposedly holds pieces of the real cross on which Jesus was crucified.

11 11. The Niccoline Chapel

You've heard of the Sistine Chapel, but have you heard of the Niccoline Chapel? The fifteenth century Chapel is hidden away in the Apostolic Palace. The walls are covered in beautiful frescoes painted by the Florentine artist Fra Angelico.

Until recently, the chapel was visited only by those most privileged visitors to the Vatican. If you weren't a diplomat or a special guest of the Pope there was a fat chance you'd have of seeing the Chapel. For the first time however, the Chapel is being opened to the public. How do you get in? You have to schedule a place in advance on one of the Hidden Museums guided tours.

10 10. The Bramante Staircases

Very few people know of the Bramante Staircase before visiting the Vatican, let alone the fact that there are actually two. The modern Bramante staircase was constructed in 1932 and is spectacularly designed as a double helix. All visitors to the Vatican Museums get to descend the staircase at the end of their tour and no surprise, it has made a splash on Instagram and Pinterest.

However, only a select few get to view the original staircase. The original staircase was built in 1505 and gets its name from Donato Bramante. Similar to its copy, the staircase is a double helix and is adorned with columns. Like the Niccoline Chapel, it is now open to those who book a place on a Hidden Museums tour.

9 9. The Raphael Rooms

These rooms are really no secret, but compared to the Sistine Chapel, the Raphael Rooms get a surprisingly fewer number of visitors. Somewhere along the lengthy tour of the Vatican Museums, many visitors opt to skip some of the rooms and head straight to the Sistine Chapel. This is a mistake.

The rooms are part of the historic papal apartments where Pope Julius II chose to live. As is obvious from their collective name, the four rooms were painted by Raphael, but they were also painted by his school who actually had to complete the final room without him after he died in 1520.

8 8. Collection Of Contemporary Art

Again, this gallery is no state secret. However, it is one that many visitors bypass as they scramble over each other to see Michelangelo's ceiling. Many people do not associate the Vatican with modern art, which was one of the reasons Pope Paul VI initiated the project. Even popes can be trendy.

The collection now includes about 8000 pieces of art. Don't worry, you don't get to see all of them. The collection does have a few gems that you shouldn't miss by famous artists including Van Gogh, Matisse, Chagall and Salvador Dali. If you thought the Catholic Church was out of touch and antiquated, just wait until you visit this collection.

7 7. Michelangelo's Self Portraits

Though it has stared down at visitors to the Pauline Chapel for hundreds of years, this self portrait has only recently been uncovered. Here Michelangelo depicts himself in a blue turban in his fresco of the 'Crucifixion of St Peter.' Michelangelo's likeness in the Pauline Chapel is a much less twisted representation than his other self portrait in the Vatican.

His more widely recognised self portrait in the Sistine Chapel cannot be described as anything other than monstrous. One can only wonder at what he was trying to convey. The portrait is part of Michelangelo's monumental work, 'The Last Judgement.' Can't see him? You'll find his face on St Bartholomew's flayed skin.

6 6. The Room Of Tears

This is possibly one of the most secret and exclusive rooms in all of the Vatican. Chances are you will never get to see it. The name suggests that it might be some sort of torture chamber but in fact, it is the exact opposite.

To put it succinctly, it is a glorified changing room. However, to a newly elected pope it is much more than that. It is a small room located off of the Sistine Chapel where a newly elected pope changes from his cardinal vestments into his papal robes. The room takes its name from the fact that so many popes are moved to tears by the emotion of being elected.

5 5. The Pope's Balcony

What a surprise, there is more than just one balcony in the Vatican, but this one has special significance. The balcony is the middle of three larger balconies that grace the facade of St Peter's Basilica. It overlooks St Peter's Square and is where most people get the opportunity to see the pope.

Traditionally, newly elected popes address the eagerly awaiting crowds in St Peter's Square from this balcony. Obviously, these special appearances only come around every once in a while. However, every Wednesday morning, the pope hosts a papal audience where he blesses the masses from his balcony. On days when the pope speaks, the balcony is easily recognisable as it is hung with plush red drapes.

4 4. Hall Of Pope Paul VI

This might not be a particularly special part of the Vatican in its own right, but what happens inside is an event many attendees treasure for the rest of their lives. As mentioned above, papal audiences are a weekly occurrence. Despite their frequency, the audiences are not easy to get into, especially when they are held in the hall.

Tickets to papal audiences are free and available to everyone. So why is it so difficult? Tickets to the audiences are in high demand and people often get their tickets weeks in advance and begin lining up hours before the audience is set to begin. The hall is used for audiences in winter and on days of bad weather but, it has a limited capacity. It is not unheard of for people with tickets to be turned away when the event is already full.

3 3. The Passetto Di Borgo

For centuries, this secret passageway served as an escape route for the pope during desperate times. Concealed inside a fortified wall, the passage stretches from the Vatican to the Castel Sant'Angelo where the pope could be better defended from perpetrators. The current passage dates back to 1277, but the last time the pope needed it to escape was in 1527.

After centuries of being shrouded in secrecy, today the passage is open to visitors. While it may no longer be secret, it still inspires the imagination with tales of danger and conspiracy. After all, the passage played a prominent role in Dan Brown's Angels of Demons.

2 2. The Vatican Gardens

Here is your opportunity to find your own secret spot in the Vatican, or rather, as close as you are going to get in a tour group. The Vatican gardens take up roughly half of the space of Vatican City. The gardens are carefully landscaped and complete with fountains, monuments and even a heliport. The pope certainly knows how to travel in style.

Like many sites in Vatican City, the gardens require that visitors book tickets in advance. Only small groups are allowed at any given time and these special few are allowed to explore the wonders of the gardens as part of a guided tour.

1 1. The Vatican Secret Archives

Finally, the Vatican Secret Archives remain one of the great mysteries of the Vatican. For years people have puzzled and theorised over what lies within these top secret archives. The archives reportedly hold 35000 volumes and the oldest documents date back all the way to the eighth century.

Until the nineteenth century, not even researchers and scholars were permitted inside this closely guarded space. The archives include some of the most significant documents in Catholic history and are still only open to a select few who are thoroughly assessed before being allowed access. On top of this, documents from 1939 onwards remain off limits to everyone outside of the Church. As the name suggests, we may never know everything contained in the Vatican Secret Archives.

Referemces: independent.co.uk, museivaticani.va, vaticanstate.va, citywonders.com, stpetersbasilica.info, nbcnews.com, vatican.va, bbc.com, atlasobscura.com