The site where modern-day Vatican City stands is named after the Vatican Hill on which it stands. The word “vatican” is taken from an ancient Etruscan settlement which was called Vatica or Vaticum, which meant garden, and the ancient Romans referred to it as vaticanus ager, or “vatican territory”. Agrippina the Elder, mother of Emperor Caligula, did build gardens on the site, before her son decided to built a circus for charioteers there instead. His project was completed by Emperor Nero, which is why it was named the Circus of Nero. It was in this circus that many early Christians were martyred, including, according to tradition, St Peter himself. The first basilica was built on the supposed site of St Peter’s tomb in 326 CE and the Vatican has been associated with Christianity ever since.
Read more.