Monemvasia
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Monemvasia is almost an island, joined to the mainland by a causeway linking it to the small town of Gefyra (at the top of the photo). Monemvasia consists of a large plateau some 100m above sea level, up to 300m wide and 1km long and is the site of a medieval fortress. The town walls and many Byzantine churches remain from the medieval period.
To get to Monemvasia from Gefyra you can take a bus or walk over the causeway and follow the road to the south (top left in the photo) or if you don't mind scrambling over the rocks above a 20 metre drop you can follow the well marked path round the north of the "island" to the light house at the tip (right hand side to the bottom in the photo). This route has the advantage of arriving in the medieval part of the town without passing the souvenir shops (you will not be able to avoid when leaving).
The medieval town is a strange, but very attractive, mixture of archaeological site, high end holiday resort and building site.
Once in the centre of the town one thing you probably want to do is climb to the castle above (on the skyline). To do this you have to navigate the unsigned narrow streets of the town.
This would be a lot easier if the prominently displayed map in the main square had the "you are here" red dot in the right place (you are at 11 not 12) and if the suggested route had not been demolished as part of a rebuilding project. Still well worth doing.
The view from the top over the town of Gefyra is amazing.
It is possible to drive a motorhome over the causeway to Monemvasia and it may be possible to park there for the night in low season, however this seems to be discouraged, it is also possible to park in several of the rather crowded car parks in Gefyra.
However the best place seems to be at the marina just out of town at 36.68239 23.03841.
Although not an official motorhome parking area it seems to be well tolerated with two (apparently free) power points in use and 10 vans there in April 2019.