A portion of an old-style terrace of a colonial era building inside the Red Fort premises fell apart after two pillars supporting the arch below the terrace gave away.
There were no casualties as the portion of terrace fell late at night on Monday. The building lies north of the Naubat Khana inside the Red Fort complex, a World Heritage Site.
"The exact reason behind the break down of pillars has not been ascertained as yet," an Archaeological Survey of India (ASI) official said on conditions of anonymity.
Workers at the site gave different reasons for the collapse, ranging from a strong storm to slight tremor experienced on Monday night, but there was no official confirmation.
Scaffolding has now been put up on the outer side of the building for a replacement. The partly dilapidated building, which shows traces of damage at several places, has already been undergoing repair for many months.
The ASI is carrying out various repair activities inside the Red Fort. This building — more than a hundred years old and named B4 — is part of a row of four similar looking buildings. Work at the first two buildings is almost complete while it continues at the remaining two .
The ASI is carrying out renovation of the four buildings to accommodate its museums inside the Red Fort premises. These buildings form important examples of colonial era architecture inside a Mughal era monument.
As part of the Comprehensive Conservation Management Plan, the heritage agency plans to break down all modern structures inside the Red Fort complex. That means all the buildings that were built after 1947 till 2003, when the Army was vacated, would be demolished.