La Seu d'Urgell is a town located in Alt Urgell county in Alt Pirineu, Catalonia, Spain. The town is also the head of its judicial district and the seat of the Bishop of Urgell, one of the co-princes of Andorra. It is located the most populated town of the region, with 17.4% of its population. La Seu d'Urgell and Puigcerdà together have 30% of the population of the area.

The Diocese of Urgell is a Latin Church diocese of the Catholic Church in Catalonia (Spain) and Andorra in the historical County of Urgell, with origins in the fifth century AD or possibly earlier. It is based in the region of the historical Catalan County of Urgell, though it has different borders. The seat and Cathedral of the bishop are situated in la Seu d'Urgell town. The state of Andorra is a part of this diocese.