Looming from an imposing coastal bluff near Platamonas village, 20km south of Plaka Litohorou, this well-preserved stronghold assumed much of its present shape in the 13th century thanks to Crusaders. Later used by Byzantines to defend the coast from pirates, today it's inhabited by handymen with weed whackers and the occasional lumbering turtle. Taxis from Litohoro town cost about €22.
From the parking area, pass the (unstaffed) booth and take the hilly path 150m to the castle and ticket booth. From here, follow the walls counterclockwise to understand the development of the fortress over time. The first small tower on the right dates from the 6th-century emperor Justinian, and predates much of the existing structure. The ruined Byzantine Church B was rebuilt in the 17th century.
The more extensive Church A ruins, protected by a wooden enclosure, were built over a 2nd-century-AD Hellenistic warehouse. Squint through the gloom to see faint fresco remains. At the castle's nearby northeastern edge, drink in magnificent views of sandy Skotina Beach below and Mt Olympus in the distance.
Skeletal outlines of oikous (medieval dwellings) and shops are signposted further down the walls. The final upwards turn into the archway leads to the acropolis, where the castle's deep cistern lies, under a grate. This well-protected space contains the castle's most magnificent tower, the pyrgos; unfortunately closed, it dates from the 14th century and the last Byzantine (Palaeologan) dynasty. Archaeologists believe that Late Antique Herakleion was originally here. The castle hosts concerts during the Festival Olympou.