ALSIUM (mod. Palo)  , an ancient town of Etruria, 29 M . W. by N. of Rome by rail, on the Via Aurelia, by which it is about 22 M. from Rome . It was one of the oldest cities of Etruria, but does not appear in history till the Roman colonization of 247 B.c., and was never of great importance, except as a resort of wealthy Romans, many of whom (Pompey, the Antonine emperors) had villas there . About 12 m . N.E. of Palo is a row of large mounds called I Monteroni, which belong to tombs of the Etruscan cemetery . Considerable remains of ancient villas still exist along the low sandy coast, one of which, about 1 m . E. of Palo, occupies an area of some 400 by 250 yds . The medieval castle belongs to the Odescalchi family . Near Palo is the modern sea-bathing resort Ladispoli, founded by Prince Odescalchi . See G . Dennis, Cities and Cemeteries of Etruria, i . 219 .