Spetses
One of the most historic and beautiful islands in Greece, closely connected with the Revolution of 1821. The use of private cars is forbidden on the island (except with special authorization for selected hours, roads and time periods). However, motorcycles and bicycles are allowed (and they are everywhere). A characteristic feature of the island is its traditional means of transport: horse-drawn buggies.
Its proximity to Athens (both by road and by sea), its small size (a 24 kilometer road circuit), its good roads, the architecture of its houses, its natural beauty and crystal clear sea, its social life with plenty of good lodgings, restaurants, and entertainment spots--the combination of all these (and several more) makes it an ideal place for all types of vacations.
Perhaps the most important person from the island, its main benefactor and factor in its development, was Sotirios Anargiros. One of his greatest contributions was the creation of the Anargyrios and Korgialenios School of Spetses, which aimed to educate leaders of a national caliber. Construction began in 1923, and the school was in operation until 1983.
A second important project for Spetses, which was launched by Sotirios Anargiros in 1914, was the imposing Poseidonion, which evokes memories of times past. A luxurious hotel comparable to the "palaces" of the French Côte d'Azur, it first opened its doors in 1914 and became a favorite summer vacation destination for wealthy and cosmopolitan Athenians.
See also the proposal about how to Explore Spetses, which describes 5 different tours of the island.
Sources
Including links of interest to tourists and in general basic texts by third parties about the Saronic Gulf area on Exploring Greece