Built into the basement of an unremarkable downtown block, the Settlement Exhibition is one of the more imaginative small museums in northern Europe. The centrepiece is the excavated foundation of a Viking longhouse from before 871 AD, displayed in situ under low lighting with projected reconstructions and interactive panels around it.
The exhibition does a careful, unhurried job of explaining the first hundred years of Reykjavik — the imports, the diet, the structure of the longhouse, the way the settlers found a hot spring (the "smoky bay" of the name) and built their farm next to it. Allow an hour.