Travel is a life-changing, exciting experience that begins with the exhilarating roar of jet engines and continues with foreign money, different languages and chaotic public transit. Sometimes even the hardiest of travelers just needs to bring the adrenaline down and reset their sense, and a trip to a lush botanical garden is just the elixir you can use!

There are botanical gardens in every corner of the world. These gardens serve important functions above bringing in tourist dollars. They are places of science for the study of plants, centers of collection and cataloguing for thousands of varieties of trees and flowers, and lively parts of the local community. They are also peaceful and colorful, like a living art museum.

While many botanical gardens charge an arm and a leg for admission, the following twenty gardens are free or offer free days. If you find yourself in Greece you shouldn’t miss the Diomedes Garden, or for the backpackers in Asia the Queen Sirikit gardens will show you a side of Thailand you didn’t know existed. You don’t need to travel far to relax in a botanic garden. New York’s Brooklyn Botanic Garden and Canada’s Niagara Parks Botanical Gardens offer a pleasant escape from the noise and heat of summer.

Whether you’re the adventurous backpacker or the loving couple unwinding on vacation, you will want to pencil in an afternoon at one of these amazing botanical gardens!

20 20. Botanical Garden of Brussels, Belgium

Founded in 1795, this lush garden in the northern part of the city center is a public park sandwiched between two busy districts. In 1826 a beautiful building, Le Botanique, was built by Dutch botanists and today serves as a cultural center and music venue.

Today you can escape the busy city for a lazy afternoon stroll along the paths flanked by hundreds of varieties of rare plants and flowers. Families can let the kids rip loose in the hedge maze that sits in the center of the garden, while jogging enthusiasts will enjoy the wide, shady periphery paths that surround the entire garden.

19 19. Toronto Botanical Garden, Canada

The smallest garden on this list is one of the more impressive ones. The Toronto Botanical Garden, dubbed "the small garden with big ideas" is only 4 acres in the city center but is made up of nearly 20 "city-sized gardens". Founded in 1958 by the Toronto Garden Club, today the TBG serves to give homeowners ideas for creating little ecological paradises in their city backyards.

You can stroll through the vast array of different garden setups, trees, bushes, ponds filled with coy fish and frogs and replica backyard gazebos. If you're visiting Toronto, be sure to stop by!

18 18. Imperial Palace East Gardens, Japan

Step out of futuristic Tokyo and into Japan's rich history with a visit to the Imperial Palace East Gardens. These gardens sit on the ruins of Edo Castle, and unlike other gardens on this list, the Imperial Palace East Gardens are manicured in pure Japanese style, with neat lines of trees overhanging ancient castle moats, and orchids flanking bridges that date back a thousand years or more.

The best time to visit is during the fall, when the last remaining Edo-period garden in Japan changes into bright orange, red and yellow. Stroll along paths where Japanese Emperors and warlords once strolled while enjoying the colors.

17 17. Jardin Botanico Canario Viera & Clavijo, Spain

Meaning "Botanical Gardens of the Canary Islands", Spain's most impressive botanical gardens sits on the northern end of Gran Canaria. It was established in 1910 by botanist Erik Ragnar, who couldn't find a site on mainland Europe that was good enough for his vision of a "botanical paradise".

If you're visiting the Canary Islands, then a trip to the gardens is a must. Covering 27 acres, the gardens are divided into different sections, such as "cacti and succulents". The best part of the gardens are the 400 trees, each one a native species endemic to the islands, that makes for a breathtaking stroll!

16 16. Royal Botanic Garden Sydney, Australia

Possibly the most spectacular free botanical garden in the world, the Royal Botanic Garden in Sydney, Australia is also considered the most important scientific research garden in the world! Founded in 1816, today it sits right next to the Sydney Opera House and takes up 74 acres of land in the center of the business district.

You can spend an entire day in this lush, diverse and well-organized botanical garden. Enjoy the massive collection of rare and exotic flowers from all over the world. There are guided tours, activities for children, several restaurants and cafes and a gift shop that is second to none!

15 15. Queen Sirikit Botanic Garden, Thailand

If you're in Thailand, get away from the well-trodden tourist path and head to Chiang Mei Province for a visit to the world's largest greenhouse complex. Named after Thailand's Queen in 1994, this garden was established to promote environmental conservation.

The complex is huge, and you can easily spend an entire day wandering around and checking out the awesome variety of plants, vines, peppers and spices on display. Thankfully there are plenty of hotels, hostels and villas nearby who rent to tourists.

14 14. Acharya Jagadish Chandra Bose Indian Botanical Garden, India

If you want to see the world's largest tree, then you have no choice but to visit Chandra Bose Indian Botanical Garden in Shibpur, near Calcutta. Founded in 1786 by a British army officer with the purpose of identifying all the strange and wonderful flowers in India, it has since grown to become a national Indian treasure.

Indeed, treasures abound in this 270-acre garden. A massive banyan tree sits in the middle of the park and, according to Wikipedia, it is the world's biggest tree at a whopping 330 meters in circumference! There's also the world's biggest collection of orchids, and 2.5 million other plants await you!

13 13. United States Botanic Garden, Washington, DC

Right in the middle of Washington, DC sits the USBG, established by an act of Congress in 1842. The garden is home to a tree planted by George Washington himself, as well as 4 original plant specimens from a world-circling expedition in 1838. Housed under a building made entirely of glass, it is the largest indoor garden in the United States!

Don't let its size scare you away, though. There are 10,000 living specimens in the building, the oldest of which is nearly 170 years old. Stroll along a meandering artificial brook that runs through the garden and relax in the quietest spot in DC!

12 12. Niagara Parks Botanical Garden, Canada

On the Canadian side of Niagara Falls sits one of North America's nicest free botanical gardens. Founded in 1938 and spread over 99 acres of land and adjoining the Niagara Butterfly Conservatory, the Niagara Parks Botanical Gardens is almost as impressive as the Horseshoe Falls!

Come and be impressed! The next time you're in the Niagara region, come and enjoy the late summer in North America's largest rose garden, where more than 2,500 roses bloom every year in a brilliant display of color and scent. If you want something more immersive, try for a free guided walking tour.

11 11. Old Botanical Garden Hamburg, Germany

One of Europe's older botanical gardens sits along the old medieval city walls of Hamburg. Founded in 1821 as a garden for growing medicinal herbs, today it is divided among 4 main greenhouse complexes, each housing different climates including the world's largest collection of alpine plants.

If mountain Edelweiss are not your thing, you can check out the massive fern collection or saunter over to the subtropical Mediterranean complex and see a varied collection of olive groves, laurel and eucalyptus. Kids will enjoy all the different climates in each greenhouse, so bring your family if you have one!

10 10. Botanischer Garten der Universitat, Switzerland

Switzerland is the land of mountains, Alpine lakes, secretive banking and the Botanischer Garten der Universität Basel. Situation in the town of Basel and adjoining the old University, the friendly garden was established in 1589, making it the oldest garden on this list.

Some things just age better with time, it seems. This beautiful garden is made up of various greenhouses, ponds and a massive collection of flowers of all shapes and sizes. You can spend an entire afternoon wandering along well-maintained paths and learning a lot from the hundreds of educational signs and plaques that introduce you to every flower.

9 9. Poznan Botanical Gardens, Poznan, Poland

Ponds full of koi fish, well-kept pathways and peaceful solitude that gardens are supposed to be all about await you in Poznan, Poland. The Poznan Botanical Gardens cover 40 acres of land and contain more than 7,000 varieties of flowers and plants as well as nearly a hundred ponds, each one filled with koi fish. The gardens may be free, but to feed the fish you'll need to fork out some cash as fish food is served in big metal coin-operated dispensaries.

If feeding greedy fish isn't your thing, enjoy one of a dozen greenhouses or just sit in a bench and enjoy the sounds of birds and wind.

8 8. Botanical Gardens Flora, Cologne, Germany

Gardens aren't all flowers and ponds. For a pricklier experience check out the cacti gardens in Cologne, Germany. The Botanical Gardens Flora have been open to the public since 1920 and were rebuilt after the war following extensive bombing damage. With 10,000 varieties of plants to view, most of which are cacti or ferns or palm trees, you're sure to enjoy the experience.

Expect to spend about 2 hours to tour this tranquil garden. If you get hungry, the café serves fresh, environmentally-friendly food in a picnic-style setting right in the garden! You can't go wrong with a visit here.

7 7. Diomedes Botanical Gardens, Athens, Greece

Opened in 1975, southern Europe's largest botanical garden is situated just outside the center of Athens, Greece. From within the peaceful confines of this garden the hustle and bustle of Athens melts away, and you are met with a dazzling display of Mediterranean flora and Greek statues.

Follow the (mostly nude) statues to the garden playground where families converge, and children enjoy their visit. There is a café that serves fresh food and beverages, and once you've done eating and playing, continue your meandering journey through the jewel of Athens. The best part is, you can touch the flowers!

6 6. Botanisk Have, Copenhagen, Denmark

Right smack in the center of Copenhagen, Denmark, sits the University of Copenhagen's botanical gardens. Covering nearly 20 acres, the Botanisk Have uses an impressive number of historical glass houses dating back to the mid-19th Century.

Inside and outside those glass houses grows more than 13,000 varieties of flowers and plants, and the largest house has a giant living palm from 1823 and a spiralling metal staircase that takes you to the top of the tree. Outside the glass houses a beautifully manicured park awaits you, complete with ponds, swans, park benches and winding garden paths.

5 5. National Botanic Gardens, Dublin, Ireland

5 kilometers north of Dublin, Ireland, is the National Botanic Gardens. Founded in 1795, this 40-acre garden used to have an entrance fee, but it is now free all week long. The glass houses in this garden have won architecture awards, and you can even visit the original garden that was planted here more than 2 centuries ago!

The National Botanic Gardens are a mecca for botanists and for those wanting to enjoy some peace and tranquility. More than 10,000 varieties of plants and flowers can be found here, making this the biggest and nicest garden in the European Union!

4 4. Royal Botanic Garden Edinburgh, Scotland

This garden is an active scientific study centre for plants, but that shouldn't keep you away. It's free to the public although a trip to the glasshouse will cost you an admission. Not to worry, because you can see plenty in the 72 acres of well-marked paths and gardens.

The park has many different types of gardens, recreating entire ecosystems such as alpine meadows to a Chinese hillside! The great thing about this garden is that, unlike nearly all the other gardens listed here, this one is never too crowded. So, enjoy a stroll through the most peaceful place in Scotland!

3 3. University Museum Botanic Gardens, Modena, Italy

In hot Modena, Italy, lies the University Museum Botanic Gardens, right next to Modena's Public Gardens. Open every month except August, the garden is only 1 ½ acres in size. That's enough for this little garden, however. Here you will find one of the world's largest collections of palms, fronds and herb plants all growing together.

The garden paths are made from actual stones from a Roman road, so you get a real Italian vibe by simply walking here, and weird irregular-shaped flowerbeds only add to the charm! There are three hothouses to visit as well, if Italy's scorching sun isn't enough for you.

2 2. South Coast Botanical Garden, Palos Verdes, California

These lush, breathtaking gardens are only 16 km south of Los Angeles, in Palos Verdes, California. 150,000 plants and trees from 7,000 species cover the fact that this garden was built on top of an old landfill in the 1950s!

You won't notice the old garbage under your feet, as well-maintained gravel and pavement paths take you through some stunning scenery, including an 8,000-flower rose garden. Events are put on all the time, including an Easter Egg hunt in the spring and a Halloween haunting in the fall. The garden itself isn't free, but once a month there is a free day.

1 1. Brooklyn Botanic Garden, Brooklyn, New York

Right in the middle of busy, bustling Brooklyn, New York sits the Brooklyn Botanic Garden. Home to over 14,000 plants and plenty of New York squirrels, this park is surprisingly quiet. It was founded in 1910 and covers 22 acres, and the garden is famous for its springtime blooms when 500 cherry trees all blossom into pinks and whites.

Although there is an admission to the park, you can get in free on Sundays during non-peak months (autumn and winter) and although you'll miss the cherry blossoms you should still be able to catch the 1,000+ rose bushes in full bloom.