Each aisle has its own door at the west end, making a total of five portals. All are beautifully carved with sculptures; one tells the life story of St. Stephen. The central door's 13th-century tympanum depicts the Last Judgment.

The main phase of construction is roughly contemporaneous with Chartres Cathedral (begun 1194), some 200 km to the northwest. As with most Early- and High-Gothic cathedrals, the identity of the architect or master-mason is unknown. The choir was in use (though not necessarily complete) by 1214 and the nave was finished by 1255. The building was finally consecrated in 1324. Most of the west façade was finished by 1270, though work on the towers proceeded more slowly. The north tower collapsed in 1506 and was rebuilt in a later style (1542). The cathedral has double aisles and no transepts. It has 13th-century stained glass windows: 22 original windows survive. A UNESCO World Heritage Site.