A medieval seven-arch stone bridge spanning the Arno about 8 km north of Arezzo, built in 1277. It remains in use and is one of the best-preserved medieval bridges in Tuscany. The setting is peaceful — the Arno here is wider and slower than in Florence, surrounded by flat agricultural land with the Apennine foothills behind.
The bridge is claimed (plausibly but not certainly) to be the bridge visible in the background of Leonardo's Mona Lisa. Whether or not the identification is correct, the structure is worth the short detour from Arezzo: a substantial piece of 13th-century engineering that has outlasted most of the buildings of the period. Access is free; it's a straightforward drive or cycle from the city.