The late 15th century Baia Castle was built by the over ancient Roman ruins thought to be the summer residence of Julius Caesar. On the 29th September 1538 the great eruption, with devastating effects for all the Phlegraean Fieldsi, caused serious damage to the Castle of Baia too. The castle was restored and enlarged by the viceroy don Pedro Alvarez de Toledo.
Today, this cliffside Aragonese castle with sea views is home to the Archaeological Museum of Campi Flegrei.
Visby Cathedral (also known as St. Mary’s Church) is the only survived medieval church in Visby. It was originally built for German merchants and inaugurated in 1225. Around the year 1350 the church was enlarged and converted into a basilica. The two-storey magazine was also added then above the nave as a warehouse for merchants.
Following the Reformation, the church was transformed into a parish church for the town of Visby. All other churches were abandoned. Shortly after the Reformation, in 1572, Gotland was made into its own Diocese, and the church designated its cathedral.
There is not much left of the original interior. The font is made of local red marble in the 13th century. The pulpit was made in Lübeck in 1684. There are 400 graves under the church floor.