The Brownshill Dolmen (Dolmain Chnoc an Bhrúnaigh in Irish) is a megalithic portal tomb situated 3 km east of Carlow, in County Carlow, Ireland. The capstone at Brownshill, weighing an estimated 100 metric tons, is reputed to be the heaviest in Europe.
It was built between 4000 and 3000 BC by some of the earliest farmers to inhabit the island. It is also known as Brownshill Portal Tomb, so-called because the entrance to the burial chamber was flanked by two large upright stones (orthostats) supporting the granite capstone, or roof, of the chamber. The capstone is thought to have been covered by an earthen mound and a gate stone blocked the entrance. At Brownshill both portal stones and the gate-stone are still in situ; the capstone lies on top of the portals and gate-stone and slopes to the ground away from the entrance. Not much additional information is available on Brownshill because it has never been excavated. A fourth upright stands close by and could be the remains of a forecourt. The extent of the chamber cannot be determined.