Hyderabad's most distinctive architectural feature is its badgirs — tall wind-catching towers that protrude from the flat rooftops of old houses in the historic city. Dozens of these structures survive in the lanes around the fort, looking like square chimneys. They are not chimneys: they are passive air-conditioning systems designed to catch the southwest wind that blows steadily for about 40 days from late April each year.
The badgir channels cool breezes down into the living rooms below, working most effectively in houses built around central courtyards. The design is related to similar wind-catching towers found in Iran and the Persian Gulf, adapted to the particular wind patterns of the Sindh plain. Walking through the old city lanes in the area below the fort is the best way to see them; many are in poor repair but the basic forms remain recognisable.