Sant Climent de Taüll is the largest, most well preserved, and has the most outstanding architecture out of all the churches in the Valley of Boí. The church is a basilica plan structure, that has three naves (each of them with a terminal apse), and large columns separating the side naves. One of the doorways opens on the west side of the building, with the remains of what might have been a porch. The other openings are located on the south side and on the access tower. The facades of the church do not have any decoration, but the apses have simple Lombard decorations and are built with stone and brick. The central apse on the exterior is decorated by groups of four arches, separated by half columns. The apsidioles (apses on either side of the central apse), have groups of three arches instead of four, with each of the apses having one window each. In addition, the central apse has three arched windows located on ground level and two portholes on either side of the central apse.