In Rome the devotion to St. John centers around the Lateran Basilica where Pope Hilary had erected two oratories, one in honor of St. John the Evangelist and the other in honor of St. John the Baptist. These two oratories became so famous that they gave the name of St. John to the Lateran Basilica itself.
The greatness of St. John the Baptist consists entirely in his mission of preparing the way for Jesus Christ. Therefore, he did not live for himself, but for Christ and for His greater glory. This is genuine humility, the foundation of all true greatness before God.
(Source: The New Roman Missal by Father Lasance)