A Roman Saxon Shore fort with a Norman keep at the head of Portsmouth Harbour. The grounds and St Mary's Church are worth a visit if they are open. There is a cafe inside the walls.
The tidal creek on your left as you follow the sea wall. At high tide the later shoreline path on stage 2 can flood.
Portchester Station is reachable by public transport. See the start pin on the map for the grid reference and postcode.
Use the start pin on the map. This is a linear stage, so a second car, a bus or a taxi at the finish is needed unless you reverse the route.