“If triumphal arches were conceived as historical statements, so, too, were the tall commemorative columns set up in Rome—another and even more peculiar Roman invention than the triumphal arch. The first was Trajan’s Column, entirely covered by a marble band of figurative carving winding up its shaft and originaly topped by a gilded statue of the emperor (replaced in 1588 by a statue of St Peter). It commemorated his campaigns in Dacia (present-day Romania) in AD 101 and 105–6, the main events of which are depicted in chronological sequence from bottom to top. As the column originally stood between two libraries founded by Trajan, it has been suggested that the cylindrical helix of the carving was inspired by the scrolls on which all books were then written. To read this figurative history from end to end, however, was not as simple a matter as unrolling a parchment scroll. The reader must walk round the column no less than 23 times with eyes straining ever further upwards! The scale increases slightly towards the top, but the upper registers are hard to see and impossible to appreciate and must always have been so, even when the figures were picked out in bright colors and gilding.”

—Hugh Honour & John Fleming, from The Visual Arts: A History, 1982. Everybody’s a critic.