Practical Tip: Tackling Mystras
At least half a day is needed to do justice to the ruins of Mystras. Start early in the morning to beat the tour groups, wear sensible shoes and bring water (you can refill at the monastery). The site is divided into two interconnected sections – the kastro (the fortress on the summit) and the hora (upper town), accessible from the fortress gate; and the kato hora (lower town), accessible via the main gate.
If you don't have your own wheels, it makes sense to catch a taxi to the fortress gate and walk down. If you do have a car, you can cover the lower town first (enter and exit from the main gate) and then head separately up to the fortress gate to visit the fortress and the upper town ruins (or vice versa). You can use the same ticket to re-enter at either entrance.