India, Feb. 13 -- Purani Dilli merchant Saeed Mirza lives with his siblings and their families in a 150-year-old house. It possesses architectural elements of a quintessential Walled City mansion. Every room for instance has at least one taak, the arch-shaped niche scooped into the wall.

The joint family is set to move to a recently built residence on the same street. The new "flat-style" house has no taak. Indeed, the taak, that has so long been an integral part of the Walled City's old-fashioned household architecture-it is almost a family member!- is now nearing extinction. (The custom of taak of course isn't limited to the historic quarter).

In a typically traditional Walled City mansion, the taak would be positioned at the centre of ...