This mosque was built by Prophet Muhammed after 622AD. It was built in order to read the Qur'an. Originally, the mosque was not this big and was originally built with palm trees and and walls of mud, over time as more and more Muslims began to follow the mosque had to increase in size ("Medina").
Sources: "Medina." Sacred Destinations. http://www.sacred-destinations.com/saudi-arabia/medina-prophets-mosque.htm. Accessed May 28th, 2009.
Old Jeddah
http://www.encyclopedia.com/doc/1G1-17763046.html
One of Saudi Arabias secret cities. It is the gateway into Mecca which during the pilgram journey, Hajj, it ables the Muslims to enter through atleast once in their lifetime. For a long time this city was closed off to tourists, this is why the city is an architectural wonder, because it was hidden behind other marktes and structures for many, many years ("Jeddah").
Sources: "Jeddah." The Coral Sity of Old Jeddan. http://www.encyclopedia.com/doc/1G1-17763046.html. Accessed May 28, 2009.