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(1) A measure of distance in ancient Rome equal to 1,000 double Roman steps; the same as the Roman mile (1.4835 km).
(2) Stone pillars placed, on the instructions of the Roman tribune Gaius Gracchus (153–121 B.C.), at intervals of one mile on roads leading from Rome toward the provinces. Carved on each milliarium were the road’s end points, the distance to each, and the builder’s name. At that point in the Forum from which the count was reckoned, the emperor Augustus (63 B.C.–14 A.D.) ordered that a gilded column—the “gold milliarium”—be placed. During the fourth century in Constantinople Constantine the Great erected a gold milliarium and ordinary milliaria on roads leading from it.