(St. John Lateran) San Giovanni in Laterano is the oldest and ranks first among the four patriarchal churches of Rome; it is the head of all churches throughout Rome and the world. Originally the palace of Constantine, it was later adapted to serve as the church of the Pope. The arch-Basilica was built later on the site of the original church and is known as St. John Lateran or the Lateran Basilica, and is dedicated to St. John the Baptist. The top of the facade boasts huge statues of Christ and the Apostles. In the five-arched portico, there are as many doors, the last on the right being the Holy Door, which is accessible only every 25 years, during Jubilee years. This church has survived two fires and a terrorist attack. This is Rome's cathedral; it's here that the pope officiates in his capacity as bishop of Rome. The towering facade dates from 1736 and was modeled on that of St. Peter's Basilica. The 15 colossal statues (Christ, John the Baptist, John the Evangelist, and the 12 Apostles of the church) look out on the sea of dreary suburbs that have spread from Porta San Giovanni to the lower slopes of the Alban Hills. The Papal Altar in this church is reserved for the Pope and only he can celebrate mass from this pulpit. The residence of the Popes until 1309 is also here (The Lateran Palace) and was rebuilt by Domenico Fontana in 1586. In the piazza is an ancient obelisk, dated to the 15th century BC, and parts of Nero's Aqueduct.