In the Cast Courts of the Victoria and Albert Museum in London, two enormous plaster columns rise through the full height of the room, split at the midpoint because no single gallery space in Victorian London was tall enough to accommodate the complete original. Red walls, a cast-iron skylight, medieval tomb effigies on the floor below, the Column of Marcus Aurelius visible behind — it is one of the stranger and more magnificent rooms in any museum in the world, and the centerpiece is a reproduction. The V&A made these casts of Trajan’s Column in the 1860s at the request of Pope Pius IX and Queen Victoria, who both wanted to study the reliefs without traveling to Rome. The decision proved more consequential than either of them anticipated. The original column, standing since 113 AD in Trajan’s Forum in Rome, has weathered continuously for nineteen centuries. The Victorian plaster casts now preserve detail that the stone in Rome has since lost. The reproduction is, in some respects, more legible than the original.

The Senate’s formula for praising good emperors — felicior Augusto, melior Traiano, may you be luckier than Augustus and better than Trajan — established Trajan as the standard of imperial virtue against which all subsequent emperors were measured. He was the first provincial emperor, born in Spain to a Roman family that had settled there generations earlier, and his elevation by Nerva in 97 AD represented the completion of the process by which the Roman Empire’s leadership became genuinely imperial rather than Italian. He was admired by his contemporaries, praised by the senatorial tradition that wrote most of the surviving ancient history, and still regarded by most historians as among the most capable emperors who ever held the position. His reign was also the high-water mark of Roman territorial expansion, after which the empire never grew larger and began, slowly and then rapidly, to contract.