"Originally a 16th-century palace where single noblewomen could take religious vows and bring their wealth, the Monasterio de las Descalzas Reales now houses a few nuns and a rich collection of relics (including alleged pieces of Jesus's cross and the bones of St. Sebastian); despite a rather dull exterior, the interior contains many works of art and a main staircase decorated with 16th- and 17th-century mural paintings — access is by guided tour only." - Matthew Kepnes