What building has the most stories?

Decode this picture on T-Shirt and tell what it says ?

It's a protector.
It sits on a bridge.
One individual can see directly through it, while others wonder what it hides.

What is it?

A man has a barrel filled with oil that weighs 100 pounds, and then he puts something into it. Now the barrel weighs less than 100 pounds. What did he put in the barrel?

I have no doors but I have keys, I have no rooms but I have space, you can enter but you can’t leave! What am I?

I am five letter word that is under you.
If you remove my 1st letter, then I am over you.
If you remove my 1st and 2nd letters then I am all around you.

Who am I?

what does this picture(rebus) riddle means ?

There are 3 apples in the basket and you take away 2. How many apples do you have now?

What is the centre of gravity?

I am a type of word that is spelt incorrectly or used differently, on purpose for humour. What am I?
Hint 1: You can find me in a joke.
Hint 2: I am a play on words.