The Marshall House

Saw a great pussy riot show at Kling og Bang here. i8 has a great roster of more blue-chip artists, including Roni Horn. There's also a lot of Olafur Eliasson work in the Marshall House, plus a cafe. And it is home to the Living Art Museum which showcases the work of Icelandic artists, often younger and more experimental. If you're in Reykjavík for only one day, this is a great stop.