Welcome to Rome and the Tiber River

This is the famous Castel Sant'Angelo
or Castle of the Holy Angel

'Initially commissioned by the Roman Emperor Hadrian as a mausoleum 
for himself and his family'
135 AD
Later converted into a fortress, a papal residence, a prison and finally a museum

 

I will add that this building is a 'stone's throw away' from the Vatican and it is said that 

                                                   there is a hidden passageway to and from.