The Bouboulina Museum preserves the 300-year-old house of Laskarina Bouboulina, the Spetsiot naval commander who became one of the great figures of the Greek War of Independence. The rooms are domestic rather than grand, which makes the story feel close: weapons, portraits, books, porcelain, and family pieces sit inside the house where her legend is rooted.
It is the best first stop on Spetses if you want the island to make sense as more than a pretty harbour.