As cool as Hallgrimskirkja Church is from the outside, be sure to check out the inside as well. There’s a small shop to the left as you go in the front doors. There you can purchase tickets to the observation deck. A small elevator to the deck can accommodate about 10 people if I remember correctly and the line for the elevator took about 20 minutes on my visit. Unfortunately there was a choir rehearsal during my visit so I didn’t get to go in the main sanctuary but was able to take a blurry photo through the glass. The observation deck has two levels with dramatic views of the Reykjavik area.