Fact:

When the Irish tell you that something is on the first floor, they really mean the second floor.

An example: room 113 would be on the second floor, room 213 the third floor and 013 would be on the first/ground floor.

Another example: when they clearly tell you to pick up your textbooks on the first floor and you walk in and ask at the counter they will definitely tell you to go up the stairs to the reserves desk.

Confusing? Yes.
Will I mix this up again? Probably.