Mexico City Cathedral

The cathedral in Mexico City has the usual lavishness of Latin American cathedrals, perhaps given the poverty in many countries perhaps more could have been spent on the people than the buildings.
The cathedral shows an important feature of Mexico City.  It was built in Pre-Hispanic times on artificial islands on a lake and is sinking.  The floor is sloping in different directions, they underpinned it in one direction so it started to sink on an axis lateral to the original problem.  The floor as can be seen in the picture slopes in multiple directions.