A Fortress Built on Three Histories

Heptapyrgion — "Seven Towers" in Greek — sits at the highest point of Ano Poli, the old upper town, where the hill drops away steeply toward the sea. The Byzantines built the original citadel here in the 4th century, using the elevation as the city's last line of defense. The Ottomans took Thessaloniki in 1430 and expanded it significantly — calling it Yedi Kule, which means exactly the same thing: Seven Towers.

What makes it unusual is what came next. Rather than falling into ruin, the complex became a prison — first under the Ottomans, then under the Greek state. It held political prisoners through the Civil War and the military junta, and only stopped functioning as a prison in 1989. What you're looking at today is three structures in one: a Byzantine citadel, an Ottoman fortress, and a 20th century prison — all layered on a hill fortified for sixteen hundred years.

Getting There and Getting In

The main entrance is on the south side. You can reach it by taxi in about 10 minutes from the city center, or on foot from the White Tower in around 35–40 minutes uphill through Ano Poli.

Entry inside is €10 for adults, with reduced rates for students and seniors. Opening hours are daily 8:30–15:30, though these can change so check before you visit. That said, walking the perimeter is completely free — and honestly one of the most underrated experiences in Thessaloniki.

The Prison Block You Can't Ignore

At the gate you'll immediately notice the yellow prison block rising behind the old stone walls — barred windows, three storeys, institutional and unmistakable. For much of the 20th century, Yedi Kule was a notorious political prison. The name became shorthand for a kind of disappearance — you got sent here, and the outside world didn't hear from you for a long time. It closed in 1989, and its transformation into a visitor site is still a relatively recent thing.

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The North Side: Where the Walk Earns Its Reputation

Walk around to the north side and you'll find a wide open area — completely free to access — with a gravel path running alongside some of the best-preserved Byzantine military walls in Greece. In spring, wildflowers cover the hillside right up against the stonework. No ticket, no queue, no time limit. This is the part of Heptapyrgion most visitors miss, and the part I'd most encourage you not to.

From here, heading back down through Ano Poli takes you past narrow streets and traditional tavernas with tables right alongside the walls. Keep going and you reach Trigonion Tower — close enough to combine into a single half-day walk. I covered that route in detail in this video