The summit of an extinct volcano, 251 meters high, in the middle of the city, reachable on foot in about 45 minutes from the parking area on Queen's Drive. Halfway up stand the ruins of St Anthony's Chapel, and from the top you can see all of Edinburgh — the castle, the Firth of Forth, and on a clear day even part of the English coastline.
Free access throughout the day, no ticket required. Light footwear is recommended and caution is advised on steep sections.