The monument was built in 1844 in honour of John George Lambton, the first Earl of Durham.
The Monument stands 136 metres above sea level. It was designed to be a copy of the Theseion, the Temple of Hephaestus, in Athens. It has also been linked with the Temple of Diana at Ephesus. It is built twice the size of the original.
It is 100 feet (30 metres) long, 53 feet (16 metres) wide and 70 feet (20 metres) high. The columns are each 6 feet and 6 inches (2 metres) in diameter.
The staircase which led to the top of the monument was closed after the tragic death of a fifteen year old boy on Easter Monday 1926. The Sunderland Echo reported the proceedings of the Inquest held on 7th April 1926.The boy, Temperley Arthur Scott of Castle Street, Fatfield, was killed after falling 70 feet (20 metres) to the ground.
The Monument is made of gritstone from the quarries of the then Marquess of Londonderry, on the east coast. Steel pins and brackets held the gritstone blocks together but over the years these deteriorated. Due to this and settlement as a result of mining beneath the hill the Monument was underpinned in 1978. In 1979 the entire western end of the Monument was dismantled block by block in order that damaged lintels could be replaced by new reinforced concrete ones. These have artificial stone facings and are recognisable by their buff-yellow colour. Surveys in the 1990s showed that the Monument was now stable
Penshaw Monument was acquired by the National Trust as a gift from the Fifth Earl of Durham in 1939.