Best riddles with simple answers

tricky

I'm in you, But not in him, I go up, But not down, I'm in the colosseum, But not a tower, I'm in a puzzle, But not a riddle.
The letter U.
72.70 %
70 votes
logicscary

The person who built it sold it. The person who bought it never used it. The person who used it never saw it. What is it?
It's a coffin.
72.64 %
2100 votes