The Rotonda di San Lorenzo is the most ancient church in Mantua. It is now sunk below the level of the Piazza della Erbe. It probably stands on the site of a Roman temple that was dedicated to the goddess Venus.
It was built during the reign of the Canossa family in the late 11th century. Inspired by the Holy Sepulchre church in Jerusalem and dedicated to the martyr St. Lawrence, it has a central plan and has maintained ancient features like the matronaeum (loggia for female faithful) and frescoes of the Byzantine school from the 11th-12th century. Another fresco fragment in the apse, portraying the Martyrdom of St. Lawrence, dates to the 15th century. The construction, according to the Lombard tradition, is in bricks, but has two columns and other details in marble, coming from ancient edifices.
Deconsecrated, it was used for dwellings, shops and stores, and at the beginning of the 20th century it was covered by other edifices. Later, it was restored and the external additions removed.
References:The Broch of Clickimin is a large and well preserved, though somewhat restored broch near Lerwick. Originally built on an island in Clickimin Loch (now increased in size by silting and drainage), it was approached by a stone causeway. The water-level in the loch was reduced in 1874, leaving the broch high and dry. The broch is situated within a walled enclosure and, unusually for brochs, features a large 'blockhouse' between the opening in the enclosure and the broch itself. Another unusual feature is a stone slab featuring sculptured footprints, located in the causeway which approached the site. Situated across the loch is the Clickimin Leisure Centre.