The ancient palace of the Laterani, given by the Emperor Constantine to the popes. Lateran, from lateo, to hide, and rana, a frog. It is said that Nero ... on one occasion vomited a frog covered with blood, which he believed to be his own progeny, and had it hidden in a vault. The palace which was built on the site of this vault was called the “Lateran,” or the palace of the hidden frog. (
The locality in Rome so called contains the Lateran palace, the Piazza, and the Basilica of St. John Lateran. The Basilica is the Pope's cathedral church. The palace (once a residence of the popes) is now a museum.