The Portal Tomb of Kilfeaghan is located near Rostrevor on a farm by Carlingford Lough in County Down, Northern Ireland. Portal tombs are megalithic structures found on the British Isles, characterized by two equally tall, upright stones with a door stone in between, forming the front of a chamber covered by a partially massive capstone.
This more than 5000-year-old megalithic structure stands out with a granite capstone measuring approximately 3.4 meters in length, 2.5 meters in width, and 1.5 meters in thickness, weighing around 35-40 tons. The capstone rests on five stones, three of which are supporting stones, and two are thin side stones, though they are barely visible. The true height of the structure is concealed by cairn material made up of rounded stones, in which the structure is embedded below ground level. A partial investigation revealed that the two portal stones (the taller front stones) are approximately 2.5 meters high, while the other stones are about 1.5 meters high from the ground. The structure is located at the northern end of a cairn measuring about 15 meters in length and 5.5 meters in width (similar to the one at Dyffryn Ardudwy in North Wales). The chamber entrance faces north, and the cairn likely extended further to the north originally.
An excavation at the beginning of the 20th century yielded flint flakes, bones, and pottery.