The Kastro of Trikala occupies the old acropolis hill that has been a fortified position since antiquity. The current walls are Byzantine in origin, built over Hellenistic foundations, and were subsequently modified by the Serbs and then the Ottomans. A section of the walls and several towers survive, along with a small garden park inside the enclosure.
The main reason to come up here is the view — the city spreads out below, the Lithaios river curves through it, and on clear days the Pindus mountains fill the horizon to the west. A short walk through the old Turkish quarter (the Varousi) at the base of the hill takes you past preserved Ottoman-era houses, a neighbourhood that has recently been gentrified into cafes and small restaurants.