Answer:
Riyadh (someone Else's answer <---- )
Who answered Riyadh is wrong... Riyadh is not even in Qatar. Qatar is a different country and Riyadh is a city in Saudi Arabia (in fact Riyadh is Saudi Arabia's Capital) The main city i would say is Doha, which contains most of the attractions..
For example, The Museum of Islamic Art and The Museum of Weaponry. And a Famous Beach : "The Katara Beach".