We did a walking through with the "Free Walking Tour" of Reykjavik through http://citywalk.is/. It was a fantastic tour and we really loved every moment of it. Highly recommend doing this tour at the start of your trip as you learn a lot about the country history, as well as get a ton of great recommendations from a local perspective of what to do. Special thanks to Erik our tour guide. He was informative, funny, and really engaging. We loved having the opportunity to connect with a local and get his perspective on growing up in Iceland.