You can't miss the majestic cathedral of the old city of Bern. It belongs to the Reformed Church of Switzerland. Most importantly, you can climb more than 220 steps, climb the bell tower, and enjoy the city and Alps in the distance 360 degrees. You can also climb the 90 or so steps to the spire if you wish, where you will see similar views. On the way down the hill you will see huge bells that still work. The cathedral itself is a Gothic cathedral with beautiful stained glass windows. It's worth seeing.