Iraklion's Venetian fortifications — built and expanded from the 13th to the 17th century — are among the best preserved city walls in Europe. The full circuit is about 4 km. The walls are up to 40 metres thick in places, designed to withstand Ottoman artillery. You can walk along the top of several sections; the best stretch runs from the Martinengo Bastion (where the writer Nikos Kazantzakis is buried) around to the Pantocrator Bastion above the old harbour.
The Martinengo Bastion is at the south of the city; Kazantzakis's grave, inscribed with his own epitaph — "I hope for nothing. I fear nothing. I am free." — is a quiet, slightly strange pilgrimage for fans of Zorba the Greek and The Last Temptation of Christ.