First of all in order not to be confused when planning your trip, this attraction is NOT in Reykjavik, not even close. It is probably put here by mistake.
Bardur is on Snaefellsnes peninsula which is around 2 and a half hours drive (200 km) from the capital.
The whole peninsula is amazing with lots of thins to do and see and requires at least a full day.
Bardur is a stone pieces monument from a local artist set on a beautiful nature trail.