Porta San Pellegrino, Border crossing and city gate next to Bernini's Colonnade, Vatican City.

Porta San Pellegrino is a gate in Vatican City's outer wall, standing beside Bernini's Colonnade and largely hidden beneath the Apostolic Palace. Its surviving fabric is a single semicircular stone arch flanked by low, square towers with machicolated parapets; the inner face carries the Borgia bull and eagle in high relief beneath a weathered Latin inscription.

Pope Alexander VI commissioned the gate's reconstruction in 1492 and placed his coat of arms at the structure's top. It was built as part of fortifications designed to protect the expanding settlement.

The gate's names record its past: Viridaria from the nearby Vatican gardens, and the popular nickname Porta Merdaria, apparently from an illegal rubbish dump kept beside it despite bans. It stands near the church of San Pellegrino in Vaticano and is now little used, hidden beneath the Apostolic Palace.

The gate is hard to see: it stands almost hidden beneath the buildings of the Apostolic Palace, close to Bernini's Colonnade, and sees little pedestrian traffic. The small welfare facility beside the Colonnade, with three showers and a barber's chair, is closed on Wednesdays and during large events.

The gate is also known as Porta Viridaria, from its proximity to the Vatican gardens, and from the 15th century Romans called it Porta Merdaria, apparently because of an illegal rubbish dump nearby despite the bans. It was reopened in 1823 by Leo XII to give the Swiss Guard direct access to their barracks, an access still in use.