It marks the official center of Madrid. Try to look for the “km 0” plaque on the ground, which happens to be where all distances in Spain are measured from. You can see the only string quartet of Stradivarius devices on the planet, plus the Royal Armoury that features https://fairsinmadridifemamadrid95814.blogprodesign.com/57007396/madrid-exhibitions-ifema-madrid-an-overview