There are still substantial remains of the Roman walls surrounding the colony at Colchester (Camulodunum). The more recent civic desire to protect the Roman heritage of the town is made clear in the signs discouraging exploration of the walls (‘by checking children … climbing upon or otherwise injuring it … any wilful damage to it’).
The Roman city of Verulamium (near St Albans) was placed in State Guardianship in 1931. This image from the 1970s shows the Ministry signs in place. The walls are now in the care of English Heritage.