Mystra appeared after the construction of the fortress in 1249, which was built from stones taken from the ruins of ancient Sparta. It was founded by Guillaume II de Villehardouin, ruler of the Achaean principality, which existed on the territory of modern Greece in 1205-1432. After its founding Mystra became the capital of the state.
Although in 1262 the Byzantines captured the ruler and took away the fortress. From that time the hill became actively built up and turned into a city. The building was chaotic, which can be seen even now.
The territory is large and if you plan to see everything thoroughly it may take more than 3 hours. And gain strength, as you will have to walk on the mountain slopes. The full city plan can be viewed on Wikipedia.
After the Greek Revolution of 1821 the city of New Sparta was founded and inhabitants of Mystra moved there. The medieval city began to disappear, however some buildings are fairly well preserved. In addition to the fortress, there is a Byzantine palace, some parts of which date back to the 13th century.
If you have a car the upper entrance is here N 37 04.353 E 22 21.857, and here is the lower part of the city and the museum N 37 04.548 E 22 22.160. We can also recommend the restaurant of Greek cuisine Ktima Skreka, which is located nearby N 37 04.818 E 22 21.374.
Find here opening hours and ticket prices.
Getting there: by bus from the terminal Kifissos in Athens (schedule) to Sparta, travel time about 3 hours. From Sparta Bus Station to Mystra you can get on taxi (7 km) or by bus (schedule).