Gallarus Oratory is a small, intact, drystone Christian church set in a field above the road on the northwestern Dingle peninsula. It dates from somewhere between the 6th and 12th centuries — the dating is uncertain because there is almost nothing to compare it to — and is one of the most photographed and most enigmatic of Ireland's early Christian sites. From a distance it looks like an upturned boat in stone.
The oratory is a single room about five metres long, built of corbelled stone walls that taper inward to meet at the top. The technique is genuinely remarkable: no mortar, no central support, and the building is still essentially watertight. A small interpretation centre across the field gives the background; the site itself is free and open at any reasonable hour.