Penshaw Monument is long, wide and high, making it the biggest structure serving only as a memorial in North East England. It is made of gritstone ashlar, which was yellow at first, but has darkened. The stone was originally held together by steel pins and brackets. Graffiti is present on many areas of the monument, in the form of both carvings and ink. Its foundations originally sat on limestone below the ground. The base consists of the upper stylobate and the lower stereobate—the columns sit on the stylobate, which is made of large gritstone blocks. The height of the base varies from at the south-west corner to at the south-east. When the monument was built there were no steps leading up to the stylobate. The floor consists of setts, which are pointed in mortar and laid to falls to diagonal flagstones. These flagstones direct rainwater to a central gulley.