The ancient name of Poros was Pogon and it is actually an island-pair inclusive of Sphairia, the southern, volcanic island where the modern city is located, and Kalaureia, the larger, northern island. A bridge connects the two islands. Poros, separated from the Peloponnase by only a few hundred metres, is a quiet, wooded island with scenic pine, olive and lemon groves and a pretty monastery, as well as two good beaches at Askeli and Neorio. It is lush and mountainous and a popular weekend getaway for locals and tourists. Graves on Poros have been dated to the Mycenaean period and evidence suggests that the island-pair have been inhabited since the Bronze Age. The Archaeological Museum is worth a visit and houses findings from the Sanctuary of Poseidon and other nearby ancient sites. The city's main landmark is the clock tower built in 1927 and other attractions include Bourtzi Castle, built around 1828, and the original site of the Sanctuary of Poseidon which dates to roughly 520 BC. The presence of a naval training base means that Poros Town's waterfront area is often lively and crowded at night. However, many visit Poros simply to relax and enjoy the lovely scenery and beaches.