Geograph - photograph every grid square

Originally there were only four entrances (or Gates) into the walled city i.e. Bishop's Gate, Shipquay Gate, Ferryquay Gate and Butcher's Gate - arranged in a cross pattern with the Diamond as its centre. Later were added New Gate (1789), Castle Gate (1803) and Magazine Gate (1865). The original Gates were themselves re-built in the 18th and 19th centuries.

In the United Kingdom, a scheduled monument is a 'nationally important' archaeological site or historic building, given protection against unauthorised change.
There are about 20,000 scheduled monuments in England representing about 37,000 heritage assets. Of the tens of thousands of scheduled monuments in the UK, most are inconspicuous archaeological sites, but some are large ruins.
Wikipedia: Link