Note: close ups of casts of scenes on the column are at my Museum of Roman Civilizatons gallery.

From the Enc. Brittinica: monument erected AD 106–113 by the Roman emperor Trajan and surviving intact in the ruins of Trajan's Forum in Rome. A marble column of the Roman Doric order, it measures 125 feet (38 m) high together with the pedestal, or base, within which there is a chamber that served as Trajan's tomb. Originally the column stood in the middle of a courtyard surrounded by galleries from which one could view at various levels the spiral band (over 800 feet [240 m] long and about 4 feet [1.2 m] wide) covered with low-relief sculpture that forms a continuous narrative of the emperor's two campaigns in Dacia. A spiral staircase is contained within the shaft's interior, which measures 12 feet 2 inches (3.7 m) in diameter. At first a bronze eagle had been placed on top of the column and then after Trajan's death a bronze statue of the deceased emperor, which was replaced in 1588 by a statue of St. Peter.