Cripta del Duomo di Siena (Crypt of Siena Cathedral), Siena (must see)

The crypt of Siena Cathedral is a complex of medieval archeology, located under the cathedral and rediscovered only in 1999. It contains a series of thirteenth-century frescoes that were sealed a few decades after their drafting, for this reason they are presented today with extraordinarily bright colors, making them almost a unicum in the history of art. The name of "crypt" is purely evocative: it is believed that there is another crypt of the cathedral, the original one, under the dome, in rooms that are still inaccessible today due to the risk of structure problems.

During the excavations, the foundations of the oldest apse were also found, illuminating the knowledge on the construction phases of the cathedral. Overall, the rooms that can be visited date back to the 12th, 13th and 14th centuries, such as the 13th century stone walls of what must have been the choir area and the left arm of the transept.