Basilica del Voto Nacional

The Basilica del Voto Nacional is 80 vertical metres of concrete, with some spectacular, completely unobstructed views from around the 70 metre mark. No pesky safety barriers get in the way here; it's just the city, you and a square metre of concrete perched near the very top of the tower. Fantastic, as long as you don't come to grief on one of the many spiral staircases or bizarrely proportioned ladders on the way up (also sin guard rails).

Inside the roof

If you look at the top of the left tower, and then follow down the side to the base of the dark tiles, you will see where the below photo was taken from...