Crossness is a place in south-east London. It is situated in the London Borough of Bexley, close to the southern bank of the River Thames, to the east of Thamesmead, west of Belvedere and north-west of Erith. The place takes its name from Cross Ness, a specific promontory on the southern bank of the River Thames. In maritime terms, the tip of Cross Ness, in the past referred to as 'Leather Bottle Point', marks the boundary between Barking Reach and Halfway Reach. An unmanned lighthouse stands there as an aid to shipping.Crossness is the location of a large sewage treatment works and the Victorian Crossness Pumping Station, built at the eastern end of the Southern Outfall Sewer as part of the London sewerage system designed by Sir Joseph Bazalgette and constructed between 1859 to 1865. Crossness Nature Reserve is east of the sewage works.