The Basilica of San Isidoro is an ancient Leon church on an even older site: a Roman temple dedicated to Mercury. The church itself is open for visits: the vaults below are a museum. Here are many royal tombs, and some of the finest frescoes in Spain.
  One of the most wonderful objects is the Chalice of Doña Urraca, claimed to be nothing less than the Holy Grail. Sadly, most historians do not go along with this! The photograph below is of a replica.
  Photography is not permitted in the vaults: the images here are from elsewhere.