Woolwich foot tunnel

The Woolwich foot tunnel crosses under the River Thames in East London from Woolwich in the Royal Borough of Greenwich to North Woolwich in the London Borough of Newham. The tunnel offers pedestrians an alternative way to cross the river when the Woolwich Free Ferry service is not operating. Both entrances to the tunnel are Grade II listed buildings. The south entrance is now somewhat hidden behind the Waterfront leisure centre.

More information on the Wikipedia page.