The Vajont Dam, in the municipality of Erto and Casso (Pordenone), blocks the gorge excavated by the Vajont stream, a few dozen metres from the Veneto territory.
The massive dam was built according to a first design by Carlo Semenza, director of the Hydraulic Construction Service office of the SADE (Adriatic Electricity Company); the project, dated June 22th, 1940, saw a nearly 200 metre high dam with a lake capacity of about 50 million cubic metres of water. This project was authorized by the High Council of Public Works in October 1943, but was soon replaced with a new and much more ambitious project: the so-called “Great Vajont”. Compared to the previous project, the new one “only” saw a level increase in the dam wall by about 60 metres, thus bringing the impoundment to a useful capacity of 150 million cubic metres of water.
In 1957 excavation works for the dam foundations and shoulders started. Foundation works were completed in August 1958 when concrete castings began. The dam construction works ended in September 1960: as many as 250 workers, 750 thousand working hours and 360 thousand cubic meters of concrete were needed for the dam completion.
The Construction Company was Torno S.p.a. of Milan, but the workforce was mostly taken from the local surrounding villages.
The final dam altitude is 722.50 metres a.s.l., being it the maximum impoundment and overtopping threshold level. Its height touches 261.60 metres making the dam the highest double arch dam in the world at the time of its construction. Its thickness is 22.11 metres at the bottom and 3.40 metres at the top.
The “Great Vajont” water system never came into operation. When the tragedy occurred the dam testing had not yet been completed.

After fifty years from the catastrophe the dam still represents the undisputed icon of the tragedy: the fact that it held up to the wave impact makes it, at the same time, a masterpiece of human genius and human negligence. Behind its massive shape the huge landslide that fell into the basin on October 9th, 1963, still rests: 260 million cubic metres of rock still fill half of the artificial basin.
The dam is 6 km from Longarone in the direction of Erto (PN) on the provincial road no. S.P. 251; the walkway crossing the dam crest can be visited with a guide.