I have just been to Real Madrids Santiago Bernabeu and although the outside was not that impressive,
but the inside....ohhhh.....that was really great.
So I would do a revisit of Santiago Bernabeu.

Croke Park, Wembley and Twickenham. If I have the change to go there again, I will.
And also San Siro in Milan, would do for a revisit.