A walk to Kasteli or alternatively, a walk around the old town of Spetses is a must. Take the old road behind Dapia, about 600 meters from the beach. The area was first inhabited during the Middle Ages and its name means "fortress".
Centuries ago, it was surrounded by walls and the citadel dominated the hilltop. Today, at the exact same point of the citadel is the temple of Agios Vasilios and a few meters below you can see the church of Agia Triada and other quaint churches.