Kings College

I think most people at some point have heard the Kings College Cambridge Choir - or the King singers.. The above is Kings College Chapel, where they have been recorded. It's immense and quite beautiful. I was halfway down the church when I took this photo. Can anyone tell me why they often divided the chapel in the middle? Choir stalls leading up to the alter on one side and I guess the congregation on the other, with a whopping great wall with an arch in the middle...

I've posted more photos here (or click the photo above)