One of the most important historical sites in the Peloponnese, Mystras grew up around a fortress built in 1249 on the northern slopes of Mount Taygetos. The Byzantine Empire took control soon after the original fortress was completed, and lavish palaces, churches, monasteries and libraries were added to the site. Much later, after Greece’s liberation and the founding of modern Sparta, 12 kilometers (seven miles) to the east, Mystras was abandoned. The ruins were named a UNESCO World Heritage Site in 1989; today this open-air museum stands as a testament to medieval glory. Wear sturdy shoes to navigate the steep cliffside paths.