I’m pretty sure that when you are leaving Iceland, customs will detain you if you can’t prove that you’ve taken at least one photo of Hallgrimskirkja, the church that is the most famous landmark in Reykjavik. So, here you go Iceland customs:
I was surprised by just how much the simple, light-filled interior appealed to me. During my visit, someone was practicing on the (apparently world-famous) organ, so I sat and appreciated (both the music and the fact that I was inside, where it was warmer!)
For a fee, you can also take an elevator to the top of the church for an amazing view of Reykjavik. It was windy (even windier than ground-level Reykjavik!), but definitely worth it.