The medieval Doria Castle sits on the rocky promontory above Vernazza harbour, accessible by a short but steep staircase from the main piazza. The surviving circular tower (Belforte) dates from the 11th century, built when the Genoese Republic was fortifying the coast against pirate raids. The castle walls still run along the cliffside above the harbour.
The views from the tower are excellent: the harbour below, the coloured houses of Vernazza stacked on the hillside, the sea in both directions, and on a clear day the headlands extending toward Monterosso and Corniglia. Entry fee is modest. The climb takes about 5 minutes from the piazza.