Okay-here it is. I think.
Pevensey Castle, also known in latin as Anderida. The Romans built it in the 4th century as a Saxon Shore Fort, part of a ring of fortifications around the south coast of England designed to deal with Saxon pirates. Possibly on Harleys. In the 5th century, the Saxons had been settled in Kent by the then High King of Britain, Vortigern, who was using them as mercenaries to stop the constant raids by the other Germanic tribes-the Romans had gone by then and had stripped Britain of its armies. Unfortunately, the Saxons decided that they quite liked it here and invaded from Kent into Sussex. This is the site of the first major battle, when 500 British (the natives, now called the Welsh) fought 5000 Saxons. The British were holed up in the fort. They were massacred. http://en.wikipedia.org/wiki/Pevensey
The fortress was built on the sea and had a wharf for galleys. The sea has long since retreated.
It was built in typical Roman fashion and would have been painted white and red (in stripes) as a warning to anybody-a bit like a wasp/ yellowjacket.
It has a mediavel castle inside it which saw action in the civil war between Steven and Mathilda. There are also 20th century pill boxes and gun emplacements built into the Roman and mediaeval walls.
Steffrr has been here but did little damage.
Interior (medieval castle on left)
Excavated Roman wall
Entrance to mediavel castle
WW2 gun emplacement
Aerial view from a notice board
Sheepdog playing with piglets on a nearby farm
13th century church
Museum-which includes stuff on the Britons-ie, the natives
I hope that the fortress does it-it's the site of a battle between the natives and the Saxons. If not, I guess the museum does.
All being okay, next tag is an observatory (this is Herstmonceux). Any size will do. Or just put an old telescope in front of your bike and photo that. http://en.wikipedia.org/wiki/Herstmonceux_Castle