San Zeno de l'Oselet church, Romanesque oratory in Castelletto, Italy

San Zeno de l'Oselet is a Romanesque church about a kilometre from Castelletto di Brenzone, built over the ruins of a Roman villa and surrounded by a cemetery near Lake Garda. Its interior has two naves and three apses, with late Romanesque frescoes of Byzantine influence.

The first place of worship here was a single rectangular hall of 6.70 by 5.50 metres with a semicircular apse, built in the early Middle Ages, probably in Lombard times, over a Roman villa. Around 1000 it became the community church of San Zeno, subject to the pieve of Malcesine. In the first half of the 12th century a second, lower northern nave and three apses were added, and in the 13th century the bell tower was built and the facade remade.

The interior walls feature frescoes from the late medieval period with Byzantine influences depicting scenes from the life of John the Baptist. This artistic decoration still gives visitors today an insight into the religious imagery of that era.

The church stands about one kilometre from the hamlet of Castelletto di Brenzone, within a cemetery complex on the shore of Lake Garda. It is municipal property and belongs to the Diocese of Verona. Excavations for dehumidification in the second half of the 1980s revealed the earlier walls, and remains of the first apse are still visible in the floor.

On the bell tower's pinnacle stands a metal weather vane shaped like a rooster, which gave the church its nickname "de l'Oselet" (the little bird). The rooster was chosen as a symbol of vigilance. The tower itself was added in the 13th century, set forward from the foundations of an older bell tower found beside the north-east corner.