Madrid in May
Madrid is a beautiful city, however it is quite a small one. If travelling around Europe as I was doing, I would only give yourself 2 or 3 days to explore, you can see most of the main points in the city within this time frame.
Insider Tip:Do not buy a metro or subway pass, you can walk everywhere you really need to go in the city. Also drink lots of water, the city is very hot and dry.