Castel Sant'Angelo, popularly known as the Mausoleum of Hadrian, is a towering west-bank river rotunda in Rome, Italy. It was initially commissioned by Emperor Hadrian as a mausoleum for himself and his family. Since then, it has been used as a refuge, castle, prison and museum. Initially called Hadrian's Mole, it is renowned for its colourful interior from Renaissance era additions including the statues of angels. Legend has it that the Archangel Michael appeared atop the building to end a plague spreading through Rome in 590. Later, Pope Nicholas III connected the castle to St Peter's Basilica, with a fortified corridor, and various popes have used it as their fortress. In 1900, Giacomo Puccini based the setting of the third act of his operatic masterwork, ‘Tosca’, at Castel Sant'Angelo. It is now open to the public, offering an amazing combination of history and presentation.