Parc de la Draga, on the northeastern shore of the lake, is the site of a Neolithic and Early Bronze Age pile dwelling — a lakeside village built on wooden stakes over the water, inhabited from around 5000 to 2000 BCE. It is one of the best-preserved sites of its type in the Iberian Peninsula, comparable to the famous Swiss lake dwellings, and has been a zone of active archaeological excavation since the 1990s.
The park itself has interpretive panels explaining the site and the excavation process, with views across the shallow water to where the ancient foundations lie submerged in the lake bed. There is nothing dramatic to see above ground, but the setting — quiet reeds, clear water, the faint sense of human habitation extending back seven millennia — is atmospheric.
A short walk north from the main lakeside promenade. Entry is free. The site is best appreciated alongside a visit to the archaeological museum in town.