The nave is 62 meters long and 18 meters high. The alley has 10 bays and 2 side aisles. The structure was built and oriented so that sunlight would subtly enter the center of the nave.
Every year on June 21st (the summer solstice) at noon, sunlight enters through the south side windows and forms a cross in the middle of the nave, guiding pilgrims directly to the choir.
The above collage (2 photos) shows the wooden crosses on the wall and the middle photo, the explanation of the crosses on the wall.
A rough paraphrasing of what was written in French - at the end of the 2nd World War in 1946, the pilgrims from many countries made a pilgrimage on foot, carrying 14 crosses to Vézelay in prayer to conquer the force of hatred that had destroyed the world. On their arrival at Vézelay, German prisoners of war, held in a camp nearby, asked to join the procession. They were allowed to do so and a 15th cross was hastily made. It became a powerful sign of reconciliation for the the world. Altogether there were 30 000 people.
Above photo was shot through a glass that was protecting the room. The room was dark. Either they are waiting for renovation or waiting for funds to enable the renovation work. All the windows are intact. The buildings/houses that we see in the middle window was actually a reflection of the opposite side. The dark blob that you see on your left near the left window was my head!