During religious holidays, the square is crowded with people, and it is difficult to approach to the Wall in general. The picture shows how it looks, for example, on Sukkot (Feast of Tents).
At the bottom of the photo you can see a fence - to go behind it you need to cover your head with something, if you are a man - you can wear a cap, or you can borrow a disposable skullcap specially given at the entrance. And if you are a woman, then you are a little unlucky and you, my dear, will have to stomp into a place specially fenced off for women at the Wall on the left side of the square. This is Israel, everything is different here...