The ruins of a 19th century colliery engine house, the only remaining building of a colliery which once extended over a much larger area. Coal mining at Haswell began in 1831 when the Haswell Coal Company, after failed sinkings in the area, bought the rights to a neighbouring field from the South Setton Coal Company. Success soon followed and, with the establishment of two separate pit heads, the first coal shipments took place in 1835. In 1844, however, disaster befell the colliery when an ignition of fire-damp claimed the lives of 95 men and boys. The colliery continued to be productive throughout much of the century until closure in 1896. The surrounding colliery site has been landscaped and the monument, known locally as the Haswell arch, stands isolated as a memorial to the 1844 disaster. The monument includes the remains of a beam pumping engine house of circa 1830-40, a rare survival within the north east coalfield at NZ37384224. It is built of randon, roughly dressed and coursed magnesian limestone. Three external walls remain standing, whilst the west wall will survive as a buried feature. The surviving walls have an external batter widening to a base 2 metres thick. The east wall stands to the eaves line whilst both the north and south walls are less complete. They do, however, include a number of openings and joist sockets which are important indicators of internal engine house design.