The Kastro is the walled hilltop neighbourhood that crowns Hora, a compact Venetian town-within-a-town built in the 13th century and still clearly distinct from everything below it. Enter through one of the original fortified gates and the atmosphere changes immediately: narrower lanes, taller walls, the muffled quality of a place designed to keep the wind out and, when necessary, enemies. The gate towers, the carved stone crests of Venetian noble families above doorways, and the Catholic cathedral at the centre all date to when Naxos was the capital of a Latin island duchy reaching across the Aegean.
The quarter is genuinely inhabited — this is not a preserved open-air museum but a neighbourhood where people live, hang their laundry, and maintain opinions about the tourists who thread through their lanes. The Archaeological Museum occupies a prominent building near the cathedral. Several small cafés and a restaurant or two sit at the upper edges, offering views over the rooftops of Bourgos below and the sea beyond. The Kastro rewards slow exploration: the secondary lanes away from the main circuit have the most atmosphere and the fewest people.