Cathédrale Saint-Gervais et Saint-Protais in Soissons

You're standing at Soissons Cathedral, dedicated to the saints Gervasius and Protasius. Start with the west front. It's strikingly plain, with three doorways and a big rose window above them. Notice anything odd? There's only one tower, on the south side. It's sixty-six metres tall, exactly as high as the towers of Notre-Dame in Paris, and it was clearly modelled on them. A matching tower was planned for the north side, but it was never built. The money simply ran out.