Efr-Hvolshellar is an interesting site which has three man-made caves.
There has been some dispute about the date of these caves. Originally they were thought to be of 19th century origin, as they were used to house animals until recently. More recent ideas places them earlier – indeed much earlier.
They were possibly created by Irish monks in the pre-Settlement period, or created by the earlier settlers. The argument against them being of Norse (post-Settlement date) is that artificial caves such as these are unknown in Norway at this period.
In the near vicinity there are the features of early building, but it is difficult to make out much from the ground. Unfortunately, it was much too windy to fly the drone for aerial photos.