Forte Tre Sassi (or Forte Tra i Sassi) is a fortress constructed in 1897 during the Austro-Hungarian period on the Passo Valparola. It lies between Sass de Stria and Piccolo Lagazuoi, dominating the passage between the Passo Falzarego and Val Badia in South Tyrol (Alto Adige). It was part of the large complex of Austrian fortifications built on the Italian border in the late 19th and early 20th centuries.