Innocent III (Lanzo of Sezza) was an antipope from 29 September 1179 to January 1180. His original name was Lando Di Sezze. He was the last of four antipopes (1179–80) during the pontificate of Alexander III.
In 1179, the enemies of Pope Alexander III (1159–1181) had successfully forced him to flee Rome, never to return. In his place, the Roman barons set up Cardinal Lando of Sezza as Pope Innocent III on 29 September 1179. They had the support of Holy Roman Emperor Frederick I Barbarossa. Most other European countries supported Alexander III however.
The main support in Rome for Innocent III was from the powerful Roman Tusculum families, who had set up the two previous antipopes - Antipope Victor IV (1159–1164) and his successor, Paschal III (1164–1168). The brother of the late Victor IV, out of hatred for Alexander III, gave Lando a well-fortified castle at Palombara to defend against Alexander's supporters. A few months later however, Cardinal Hugo successfully bribed the guards to gain the castle. Innocent III and his supporters were then locked up for life in the monastery of La Cava in January 1180.