Cathédrale Notre-Dame-de-l'Assomption in Clermont-Ferrand

You're standing in front of Clermont-Ferrand Cathedral, officially Notre-Dame-de-l'Assomption. The first thing you notice is the colour. This church is almost black. It's built from local volcanic stone, the pierre de Volvic. That stone is so strong that the builders could use remarkably slender pillars. Now look up at the two spires on the west side. They're just over 96 metres tall and rise high above the city's rooftops.