The Villa Farnesina is magical for me. I think every space in the building is almost fully frescoed all around and that does create a very special and enchanting ambience.
I am not a fan of Rafael, however the Galatea is one of his better works.
My favourite space is The Hall of Perspectives painted by Baldassarre Peruzzi where the frescoes fully explore architectural optical illusion, frescoed marble columns are juxtaposed with real marble, the marble floors become frescoes and continue into the horizon beyond the walls vanishing into cityscapes and cloudy skies beyond. It really is a clever space, and the sense of depth created is quite real.
Frescoes throughout the Villa Farnesina depict stories from Greek mythology and history such as The 12 Labours of Hercules, Europa and The Bull and The Marriage of Alexander The Great.