The Basilica dell'Osservanza is a church on the outskirts of Siena
. It was built around 1490 probably designed by Francesco di Giorgio and was expanded between 1495 and 1496 by Magnifico Despota Pandolfo Petrucci.
Built in the Renaissance style, the original complex was damaged during the Siege of Siena in 1554 and after it was rebuilt in the Baroque period and restored between 1922 and 1932. During the Second World
War it was almost totally destroyed by American bombing on January 23 1944, but in an ambitious post-war reconstruction project the original basilica was able to be rebuilt through photographs and evidence presented by the monks of the monastery.