Geograph - photograph every grid square

Grade I listed buildings and structures are of exceptional, even international importance. There are over 6,000 in the country. Only 2.5% of listed buildings are Grade I listed.
In Scotland the classification is Category A
Index: Link

Sir Christopher Wren was Commissioned with rebuilding a number of the Churches destroyed in the City of London, by the Great Fire of London. His office rebuilt 51 churches, not all survive.
See Link for a list of churches.
Google map of their location: Link

The Church of St Benet Paul's Wharf is the Welsh Anglican church of the City of London. Since 1556, it has also been the church of the College of Arms in which many officers of arms have been buried. In 1666, following the Great Fire of London, the church merged with nearby St Peter's. The current church was designed by Sir Christopher Wren. There has been a church on this site since 1111.
Church is grade I listed. Link

A few years ago I read a book by Mark Mason "Walking the lines" in which he walked the route of the London Underground lines, overground. I will repeat this visiting all 272 stations (some more than once). My route tries to follow the line of the railway as closely as possible, using footpaths and roads, deviations are made to make the walk more "interesting".