Islamabad was built in the 1960s to replace Karachi as the capital of Pakistan. While Karachi was the nation's economic hub, its location at the southern edge of the country made it vulnerable to naval attacks and difficult to manage for the northern regions. Islamabad was designed by Greek architect Constantinos Apostolou Doxiadis in a grid-like pattern, divided into various sectors such as administrative, diplomatic, and residential zones. The city is famous for its abundance of greenery and the Margalla Hills National Park, which forms its backdrop. A major landmark is the Faisal Mosque, which was the largest mosque in the world upon its completion in 1986. Unlike traditional mosques, it lacks a dome and is designed to resemble a Bedouin tent. Islamabad is considered one of the most organized and urban-planned cities in South Asia, contrasting sharply with the chaotic, historic energy of its 'twin city,' Rawalpindi, which sits just a few miles away.