It marks the official center of Madrid. Try to find the “km 0” plaque on the ground, which can be where all distances in Spain are calculated from. You'll be able to see the only string quartet of Stradivarius instruments on this planet, as well as Royal Armoury that https://services-for-organisers-i93715.blogpixi.com/35982306/5-easy-facts-about-fairs-and-congresses-described