Right in the middle of the madding crowd that is the city of Kolkata lies a green haven of tranquility - the famous Indian Botanic Garden that harbors in its sprawling 273 acres not just 12,000 trees and shrubs but also many a weary city dweller taking refuge in its soothing spaces.

One of the most renowned gardens in the world, the 220-year-old Indian Botanic Garden is a crucial landmark in the Dominque Lapierre's City of Joy, only eight kilometers from the main Howrah railroad station and 25 km from the airport.

Visitors can walk under the shade of a wondrous and sprawling banyan tree that has been sheltering people for the last 250 years and is the oldest in the world, listen to the chirping of birds, spot a butterfly or just walk into a big family of exotic plants while taking a leisurely stroll.

Foreign tourists, nature lovers and researchers coming to this part of India, the garden welcomes them all into its undisturbed greenery and century-old herbarium specimens.

The garden on the west bank of the Ganges has become a living repository of more than 12,000 trees, shrubs and climbers representing over 1,400 species together with a large number of wild cultivated herbs.

The garden, earlier called Royal Botanic Garden or 'Company Bagan'- bagan means garden in Bengali - was established in 1787 by Colonel Robert Kyd under the patronage of the East India Company.

The first wonder that greets the visitor is The Great Banyan Tree, which finds place in the Guinness Book of World Records as the oldest tree till date, and spreads its 2,880 prop-roots over 1.5 hectares of land.

Legend has it that the tree (Ficus benghalensis, Family: Moraceae), which gives the appearance of mini forest, existed on a Phoenix tree (date palm) before the establishment of the garden.

In 1925, the tree was severely infected by wood rotting fungi and its main trunk, measuring about 16.5m in girth and 1.7 m above ground level, was removed two years later.

"Since then, we have become more conscious about preserving this tree. Now we take regular care for the nourishment of every young root coming out from the branches of the banyan tree. Sometimes it takes 10 years for a single prop-root to come from branches to soil," said Girija Shankar Giri, superintendent of the garden.

He said scientific approach was only one aspect of preserving and conserving the old banyan tree, which is really more of a heritage property.

"The authorities can only nourish the tree by spraying insecticides and monitoring the roots to prevent any fungus attack. We want people to be aware of its importance and they should take care of this priceless possession in future," said Giri.

The garden also boasts a rare collection of native and exotic plants and a large number of endangered plants.

"It's a not a horticulture or fruit garden like you can see in every nook and corner of the city. It's a place where we preserve rare species and try to nourish those plants in a different environment. We don't even try to give the garden a very glitzy look. We are more interested in keeping the primitive flavour in it," he said.

Apart from The Great Banyan Tree, there are other attractions too like the 'mad tree', none of whose leaves are similar in size or shape. Experts rather poetically describe the tree as not only mad but also as 'unity in diversity', solely an essence of Indian culture.

"We are amazed with the beauty and variety of the Indian Botanic Garden. Before coming to India, we had no idea about this garden. But it's so beautiful that we can't explain its beauty in words," said Alice, visiting with her family from London, who spent their entire day hanging around the Indian Botanic Garden.

A six-member Japanese tourist team was also fulsome in its praise. "The banyan tree is just mind-boggling," said a tourist strolling under the vast canopy of its shade.

According to green activist Subhash Dutta, the upkeep of the garden was most important: "It's the largest manmade plant kingdom in the entire Southeast Asia and it should be maintained with proper care, specially for the sake of future research works and to keep the nature alive."

Garden authorities are all set to make the place more tourist friendly.

Battery-driven cars taking tourists over the vast greens, couples boating in placid lakes with trees playing cupid and special facilities for the elderly to roam, the garden is now readying for a makeover.