When visiting Tiananmen Square are you allowed to take pictures?

If you just wander around the square, you can take the pictures on the square without limitation.

If you want to enter some of the halls or musuem on the square, some of the places are not allowed to take photos. As I know, the cameras are not allowed to taken into the Memorial Hall of Chairman Mao, let alone taking photos. There are the signs reminding you not to take photos.

Thank you :-)