Tehran has grown dramatically since Mohammad Khan Qajar chose it as the capital of the Qajar dynasty in 1796. Despite the occurrence of earthquakes during the Qajar period and before, some buildings still remain from Tehran's era of antiquity. However, most of Tehran's historic architecture has been obliterated by the wave of hasty modernization that swept through the capital over the last 40 to 50 years. Of the eight city gates of old Tehran, none remain today.