Grade I heritage buildings on Ballygunge Circular Road now have the blue heritage plaque of the Kolkata Municipal Corporation on their gates.

The plaques were putup in the first week of October. Among the buildings sporting the tag are Thapar House, Pathhar Kothi and Tripura House.

Partha Sarathi Samanta, the director-general of the KMC’s heritage and environment department, said: “It is part of our drive to install heritage plaques on all listed Grade 1 properties in the city. Till now we have put up plaques on 500 houses. This is to let people know of the heritage status of the properties.”

Pathhar Kothi has been on the list of Grade I heritage buildings since the 1990s. The blue plaque lists 34/1B-L as Kolkata Heritage. There are several cottages on the west side of a common private road, at 34/1 Ballygunge Circular Road, which are called Pathhar Kothi because of the colonial-style individualbungalows.

Bikram Dugar, the owner of 34/1L, a quaint stone house, said: “These are called Pathhar Kothi because they are built of concrete blocks. Here 10 houses have been graded as heritage houses because of the architectural style that includes slanting roofs, wooden lattice work and Burma teak wooden flooring. These were built in the 1920s for English military officers.”

Dugar came to own his house through inheritance. His great grandfather, Narpat Singh Durgar, bought nine bighas of land at the site along with these 10 stone houses from Eastern Bank, which later merged with Chartered Bank, as the entire property was mortgaged to it.

“Slowly, the houses along with the land passed hands. Now the eastern side of the common road has been developed and large multi-storey buildings have emerged. But the old stone houses have been left intact on the western side,” said Dugar.

Thapar House — 35/1 Ballygunge Circular Road — is a landmark gated property that sprawls over Ballygunge Circular Road and Hazra Road. Renovated and maintained impeccably, the yellow-coloured heritage house has a large portico, stained glass windows and exquisite cement carvings. The house also has a heritage plaque from Intach, Calcutta.

G.M. Kapur of Intach said: “It was built by Lala Karam Chand Thapar in the 1920s. It is a magnificent mansion with a large lawn and a swimming pool. The house was painstakingly restored by his grandson Vikram Thapar some 15years ago.”

Thapar House has some exquisite interiors with old colonial furniture, artwork and priceless collections. Some of the rooms are opened for private and public functionsoccasionally.

Tripura House on Ballygunge Circular Road has been in news because of the construction of a highrise on a part of the land on which the stately mansion stands. The yellow-white-domed house with its sprawling garden and black gate, sporting the coat of arms, is owned by the family of the erstwhile maharaja of the north-eastern state.

Tripura House was built in 1891 by Maharaja Bir Chandra Manikya and renovated by Maharaja Bir Bikram in 1931 with some additions andalterations.

A quaint red-brick bungalow, right opposite the Ballygunge Science College campus at 53 Ballygunge Circular Road, has also got the heritage plaque of the KMC. The bungalow stands dilapidated and is hidden from the gate.

The Airmen’s Mess at 61 Ballygunge Circular Road, the house at 24/1A Ballygunge Circular Road that was designed by Charles Correa and a mosque at 17 Ballygunge Circular Road are among the other properties in Ward 69 that got the plaque.

“The blue plaques, which let people know of the heritage status of the buildings,can also act as a deterrent to land sharks,” said a KMCofficial.

The civic body’s website says no external changes can be made to Grade I properties and the usage should be compatible with the heritage category.