Riyadh, of course, is the country's capital as well as the historic home of the Nejdi Salafist culture that characterizes the country today.
Jeddah has played an important role in history as the capital of the Hejaz region, port and way station for Muslim pilgrims making hajj or umrah for centuries. Soon it may also be home to the tallest man-made structure in the world.
Mecca is, of course, the holiest city in Islam. The city that all observant Muslims pray toward five times a day. Muhammad's home town. A byword for any place that attracts pilgrims, devotees or visitors.
Medina is the 2nd holiest city in Islam and has played an important role in the religion's history.
Al-Ahsa used to be one of the ten largest cities in the world, as you can see on my Top 10 Cities Through History quiz.
Ta'if is the summer capital of Saudi Arabia.
Dammam is an important port city, home to Saudi Aramco.
The others are less significant.