Gun free zone

When you enter Universal Studios in Orlando, there is a search of your bag to ensure that you are not carrying in any weapons. It is purely for show. There are numerous security holes. There is a mini golf course, located in the nominally 'sterile' area beyond the checkpoint. Only a three foot tall fence separates the mini golf course from the area where cars are dropped off for valet parking. Getting a weapon past the checkpoint here involves simply getting out of your car in the valet parking area, throwing the weapon over the fence to an accomplice.
You can also enter the 'sterile' area by taking a water taxi from one of Universal's on site hotels, and bypass security that way. There are other ways, as well. Security theater.

There are other places that claim to be secure. Courthouses are a good example. Until a person kills a judge in his chambers.

If the powers that be cannot even safeguard a judge in his chambers inside of a building filled with armed cops, and metal detectors, how can the guarantee the safety of a disarmed public? The answer is: they can't. You are the person most responsible for your own safety.