Comptroller and Auditor General (CAG) Shashi Kant Sharma unveiled the commemorating stone.
Constructed in 1910 by Major Lyndhurst, the Assam-type Bungalow No 1 on the estate has six large rooms with wooden floors and enclosed on four sides by double walls of bamboo and plaster.
It was rented out by its the then owners, who hailed from Assam's Goalpara district to the Government of India in the 1950s. The government bought it in 1962.
The state government had officially written to the AG informing of the heritage value of the building last year.
He said CAG was keen about maintaining heritage buildings across the country and the British-era Gordon Castle in Shimla, which was housed the AG office in Himachal Pradesh and was destroyed in a blaze last year, would be reconstructed.
"I am taking up the project to rebuild Gordon Castle. We will undertake reconstruction in the same manner as it stood before the fire. This is our commitment to heritage sites," Sharma said.
