The Cathedral of Messina is a Norman foundation from the 12th century, but the building you see today is largely a reconstruction. The 1908 earthquake destroyed the city, and what fire and rubble spared, World War II bombing finished. The current cathedral was painstakingly rebuilt using original stonework where it survived, and the facade has the distinctive alternating patterns of Norman-Arab architecture. Inside, the apse mosaics are genuine medieval work, miraculously preserved.
The campanile clock is the reason most people make a point of visiting. The tower is covered in animated bronze figures, astronomical dials, and mechanical scenes that move throughout the day, but the full performance at noon is the one worth timing your visit around. The diorama includes a crowing cock, the days of the week represented as planetary chariots, and a large lion that roars on the hour. It sounds faintly ridiculous described in words and is genuinely magnificent in person. The cathedral piazza is also Messina's main civic square, pleasant to linger in outside the noon rush.