Poros is a small Greek island-pair in the southern part of the Saronic Gulf, about 58 km (36 mi) (31 nautical miles) south from Piraeus and separated from the Peloponnese by a 200 m (656 ft) wide sea channel, with the town of Galatas on the mainland across the strait. Its surface area is about 31 square kilometres (12 sq mi) and it has 3,780 inhabitants. The ancient name of Poros was Pogon. Like other ports in the Saronic, it is a popular weekend destination for Athenian travellers. Poros consists of two islands: Sphairia , the southern part, which is of volcanic origin, where today's city is located, and Kalaureia , also Kalavria or Calauria (meaning 'gentle breeze'), the northern and largest part. A bridge connects the two islands over a narrow strait. Main Sights of the island are: The town of Poros, with its neoclassical edifices, is built amphitheatrically on the slopes of a hill. Its most famous landmark is a clock tower, built in 1927. The Archaeological Museum of Poros, at Korizis Square, houses findings from the Sanctuary of Poseidon, from ancient Troizen, and from other archaeological sites nearby. In the northern part of the island are the remains of the Sanctuary of Poseidon, the centre of the Kalaureian amphictyony. The exact date it was built is not known, although researchers estimate it to have been around 520 BC. The dimensions of the temple, which is of the Doric order, are 27.4×14.4 m. There are six columns on each short side and twelve on each long side. It was here that Demosthenes, the famous orator, poisoned himself with hemlock in 322 BC fleeing from the Macedonian Governor Antipatros. Poros was the site of the first naval base in modern Greece, established in 1827 during the Greek War of Independence. Most of the activities of Poros naval base were moved to Salamis Naval Base in 1881. The site is still used today by the Hellenic Navy as a training centre for naval personnel. Bourtzi castle. It was built by von Heideck at around 1828, at the place where an old church of St. Constantine had stood. The island was given to the Poros monastery from 1770 on by Antonios Serfos. The stand off between Hydra island and Capodistrias gave the cause for severe fight here on 1831. Poros Shell Museum. Founded in 2006, a permanent exhibition of Shells from the Greek Seas is displayed at the Chatzopouleios Library. More info can be found on the webpage. The Holy Monastery of Zoodochos Pigi, founded in 1720 a.d is located 4 km east of the main city of Poros island is built on the slope of a pine forest. In 1814, a group of monks from Mount Athos, took refuge in this Monastery. A few years later, these monks founded the Zoodochos Pigi Monastery at Longovarda in this island of Paros. Katholiko, Is a bacilica with a dome and a tower like belfry being the main church of the monastery.
UPDATE AS OF MAY 2022: The Municipality of Poros decided to paint the rusty metal handle and unfortunately a muggle probably removed the cache. So, at the moment, there is no cache in place