The Plaza de Isabel II is popularly called the Plaza de la Opera and is close to the Royal Palace. It is a very busy plaza where one can find the Opera House and where many downtown streets like Calle Arenal end.
This castle is rumored to be one of the most haunted places in the world. During a renovation workers discovered an oubliette, which is a dungeon that can only be accessed through a roof hatch. Inside they found three cart loads