Another trip flash-back, the tower and the Duomo at Pisa.
I learned the tower had actually started to lean by the time they had finished the 3rd floor - so they built the rest of it on a curve to compensate. Madness. We had already climbed the claustrophobic 500+ stairs to the top of St Peter's at the Vatican and Torre del Mangia in Siena, so skipped climbing this one - the thing is clearly going to fall over someday.