The Western Wall stands as the holiest site in the world for Judaism. It's a remnant of the Temple Mount, destroyed millennia ago by the Romans.
Why so important? While some other parts of the Temple Mount apparently remain standing, this wall lies closest to the Holy of Holies, the most sacred site in traditional Judaism. The Holiest of Holies refers to the inner sanctuary of the temple where none other than the Ark of the Covenant held the Ten Commandments.
The plaza, and really, the Wall itself, are bisected by another fence. This one divides left from right, men to the left, women to the right. A guard chases down anyone entering the wrong side. Apparently there is some amount of argument as to the separation and equality with which its applied.
Security around the Wall and plaza is understandably tight. A well armed Israeli sentinel gives me the evil eye as I snap his photo. A few of them stood watch just prior to the entry to the plaza.
Approaching the wall from the male side; In the background one can see the temporary Mughrabi Bridge, providing non-Muslim visitors direct access to the Temple Mount.
The bridge it replaced and the construction of this one are the source of considerable controversy, international criticism, some riots, even calls for a third Intifada. See this NY Times blog for one opinion on the situation. See The Guardian for a distinctly Muslim view of things and finally, Beliefnet, for a possibly balanced view of the situation.