When the work originally commissioned by the Opera della Metropolitana in 1999 to recuperate the spaces connected to the Oratory of San Giovannino and San Gennaro was expanded to include the area beneath the Cathedral chancel, it brought to light a totally unexpected space decorated with a cycle of paintings in the second half of the 13th century.
The absolute novelty and superb quality of the frescoes rediscovered after so many centuries extends our knowledge of 13th century wall painting immeasurably, providing us with crucial evidence of the birth and early development of the Sienese school of painting. Nor was the discovery confined solely to figurative art. The archaeological and architectural finds, in perfect harmony with the paintings, are also of immense interest, and indeed many of the structural elements are still abundantly decorated, offering us a new and unusual image of painted architecture. Together with the discovery of the foundations of the church's apsidal section, this has shed valuable light on the phases of the Cathedral's construction and on the numerous still unresolved problems surrounding it.