The small Byzantine church of Saint Nicholas sits on a rocky peninsula at the edge of the old harbour, looking out across the Mirabello Bay. Built between the seventh and ninth centuries, it gives the town its name. The church has been in continuous religious use for over 1,200 years and still holds Orthodox services.
Inside, the frescoes date from different periods of the church's history, the earliest being Iconoclastic-era survivals. The church is small — it holds perhaps thirty people — but the combination of its antiquity, its setting above the water, and the survival of its frescoes makes it worth a visit. It is open to visitors year-round.