This picture was taken in the Chellah in Rabat, and shows the ruins of a mosque and madrasa, as well as the tombs of three walis in the background. "Wali" in this context is usually translated as "friend of God," and is roughly analogous to a Christian saint. They were believed to have baraka, or divine blessing, which was often transferred to their tombs. The tombs thus became pilgrimage sites. The most important site here is actually not visible in this picture, and that is a small pool behind the mosque/madrasa complex with eels in it. Some believe that feeding eggs to these eels helps with fertility problems.