3 days in London

Hello!!!!!

I will go to London for 3 days (january 28, 29 and 30th).
I want to know what kind of monument I have to visit or ignore these 3 days.

And if you have some others suggestions...

I've never been there.
But i heard about Tower Bridge, Big Ben, Mrs Tussaud's, Buckingham, Westminster.
Same as everybody i guess.