AMPSANCTI or AMSANCTI, VALLIS, a celebrated valley and small sulphurous lake in the heart of the Apennines, in the country of the Hirpini, about 10 miles SE. of Aeculanum. The fine description of it given by Virgil ( Aen. 7.563—572) is familiar to all scholars, and its pestilential vapours are also noticed by Claudian ( De Rapt. Pros. 2.349). It has been strangely confounded by some geographers with the lake of Cutiliae near Reate; but Servius, in his note on the passage, distinctly tells us that it was among the Hirpini, and this statement is confirmed both by Cicero and Pliny. (Cic. de Div. 1.3. 6; Plin. Nat. 2.93.) The spot is now called Le Mofete, a name evidently derived from Mephitis, to whom, as we learn from Pliny, a temple was consecrated on the site: it has been visited by several recent travellers, whose descriptions agree perfectly with that of Virgil; but the dark woods with which it was previously surrounded have lately been cut down. So strong are the sulphureous vapours that it gives forth, that not only men and animals who have incautiously approached, but even birds have been suffocated by them, when crossing the valley in their flight. It is about 4 miles distant from the modern town of Frigento. (Romanelli, vol. 2. p. 351; Swinburne's Travels, vol. 1.128; Craven's Abruzzi, vol. 2. p. 218; Daubeny, on Volcanoes, p. 191.)
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