We are planning to be in Cologne for two nights in the middle of September, but the hotel rates seem to have doubled (or require a four-night stay) during the second and third weeks. What is happening there?
There's something called the Photoszene Festival running then. It begins in August. I have no idea whether it's big enough to affect hotels to the degree you've observed.
PhotoKina, a huge International photography and imaging trade show is at the Koeln Messe September 20 to 25. I was in Dueren about 16 years ago while it was going on. Even the hotels in Dueren, which is about 15 miles out of town, were booked with people visiting the trade show and commuting to Cologne.
Thanks. I had seen a references to it but did not envisision the size. I can reschedule the trip.
The PhotoKina is the world's largest trade fair for photography. With 180,000 visitors it's no wonder that hotels fill up.