Madrid, Spain: Teatro Real

Let's see - a really nice, old, well-decorated, cube-like building in the middle of a world capital in Europe? The first guess is always an opera house. In this case, you'd be right.

The Teatro Real is located right across the street from the Royal Palace. The facility took 32 years to build, finally opening for business in 1850. Then it was closed from 1925 due to structural damage, and didn't reopen until 1966 - when it was used for symphonic music. That plan lasted 25 years until 1991, when it was updated again as an opera house. 

This is considered one of the great such facilities in Europe. It has hosted a variety of events over the years. There are tours of the building, so you can see what's inside. Or, you can simply watch the video: