The structures, weathered by the salty air, open the door to Karachi's colonial scars, researchers say, pointing out that many of the original owners were among millions of Muslim and Hindu refugees who fled their homes amid communal and religious violence that accompanied the end of British rule in India in 1947 and the creation of Pakistan.

"Every brick of the heritage building narrates a story of those who left in 1947," said Akthar Baloch, a researcher who has written several books on Karachi's heritage. "They built them with love and affection.

"When people like me feel bad looking at the neglect of these heritage sites, one wonders how the families of the owners must feel if they ever visit Karachi."