The square tower.

A 60 km around the “bassin de Thau” with my husband and friends , with electric bikes with a heavy heat waves (40 degres Celsius), fun.

[Mags]

Interesting structure!

[Bucktree]

Sturdy lookout tower. Nice find.

[Kathy]

Left over from WWII? I'll bet it's a lookout and/or a place for gunners to watch the coastline.