Archaeology breakthrough as secret 'papal palace' found under major city

Archaeologists have made a stunning discovery, which has been described as "of extraordinary importance" to . The so-called is celebrating Jubilee Year 2025 - a major Catholic festival that is held every quarter of a century.

The estimates that over 32 million pilgrims will travel to the Italian capital for the celebrations that started on Christmas Eve last year and will run to January 6, 2026. Several parts of the city have been subject to renovations in the run up to the event, including the Piazza San Giovanni in Laterano.

The square is located near the Basilica di San Giovanni in Laterano, the oldest papal basilica in the city.

During renovation work at the piazza last year, researchers came across complex architectural structures, including a wall.

The wall was found to be constructed from large blocks of volcanic rock bricks, that had once belonged to buildings no longer in existence.

believe the wall - which dates back to between the 9th and 13th centuries - belongs to the Patriarchate.

The Patriarchate was a residence for leaders of the church and originally was made up of a grand reception hall called the monumental basilica.

The structure was later developed and expanded, eventually becoming the official office of the until 1305.

Thereafter the Papacy was temporarily moved to Avignon in France until its return to Rome in January 1377.

According to Italy Ministry of Culture, the wall was built during a time of turmoil amongst aristocratic families in .

This suggests the wall was designed to defend the basilica from external attacks.

Italy's Minister of Culture Gennaro Sanguiliano said the discovery was of extraordinary importance" to history.

He added: "The discoveries of Piazza San Giovanni in Laterano are yet another demonstration of the richness of the territory of Rome, an inexhaustible mine of archaeological treasures.

"Every single stone speaks to us and tells its story: thanks to these important finds, archaeologists will be able to know more about our past."