Interlacing patterns and celtic knots on the roman church of San Michele in Murato, on the island of Corsica.
This small church in the Nebbiu region was built in the 12th century, when the island was under Pisan domination. It is made of a pattern of alternating white (limestone) and green (serpentinite) stones, some of which are sculpted with snakes, birds and other animals, characters and faces, and celtic knots, interlacing circles and intertwined snakes.
It is the case for example of those two arrow slit windows on the south facing wall:
The San Michele church belongs to the Pisan Romanesque art style, as it was built under the Republic of Pisa. Although it is way smaller you can find similarities in style and details with churches and other buildings in Pisa, Lucca and others places in Tuscany or Sardinia.