Theimussa is an ancient Lycian settlement located near Üçağız Village in the Demre district of Antalya, Turkey. Although detailed historical information about the city is limited, an inscription discovered in the area indicates that the settlement dates back to the 4th century BCE.

Theimussa is situated on the northern shore of Üçağız Bay, a natural harbor. The bay, surrounded by green hills on three sides, provides a safe haven for boats. Among the ruins found in the village, tomb structures are particularly prominent. Additionally, near the shore, there is a doorway with its jambs still intact, as well as the remains of a tower on a low rocky area.

The city is known to have been part of the Lycian League and was a maritime settlement. Inscriptions on tombs mentioning the enforcement of severe criminal penalties in Myra or Kyaneai suggest that Theimussa functioned as a naval unit affiliated with these cities.

Address: Kaleüçağız Neighborhood, Demre/Antalya, Turkey