Ulldecona Winter Main Festival Activity · Ulldecona, Montsià, Tarragona Image of Ulldecona, not of the place itself. Ulldecona's Festa Major d'Hivern is held beside the Gothic church of Sant Lluc, begun in 1373, in a town that preserves rock shelters with prehistoric rock art included on the Unesco World Heritage list. Photo: Gordito1869 (CC BY-SA 4.0) What to see and do in Ulldecona