Trajan's Column - Spiral Stair

Spiral Stair

The interior of Trajan's Column is hollow: entered by a small doorway at one side of the base, a spiral stair of 185 steps gives access to the platform above, having offered the visitor in antiquity a view over the surrounding Trajan's forum; 43 window slits illuminate the ascent.

The column stands 38.4 m high from the ground to the top of the statue base: Located immediately next to the large Basilica Ulpia, it had to be constructed sufficiently tall in order to function as a vantage point and to maintain its own visual impact on the forum. The column proper, that is the shaft without the pedestal, the statue and its base, is 29.76 m high, a number which almost corresponds to 100 Roman feet; beginning slightly above the bottom of the base, the helical staircase inside measures a mere 8 cm less.

The column is composed of 29 blocks of Luna marble, weighting in total more than 1100 t. The spiral stair itself was carved out of 19 blocks, with a full turn every 14 steps; this arrangement required a more complex geometry than the more usual alternatives of 12 or 16. The quality of the craftsmanship was such that the staircase is practically even, and the joints between the huge blocks still fit accurately. Despite numerous earthquakes in the past, the column today leans at an angle of less than half a degree.

Trajan's Column, especially its helical stairway design, exerted a considerable influence on subsequent Roman architecture. While spiral stairs were before still a rare sight in Roman buildings, this space-saving form henceforth spread gradually throughout the empire. Apart from the practical advantages it offered, the design also became closely associated with imperial power, being later adopted by Trajan's successors Antoninus Pius and Marcus Aurelius. In Napoleon's time, a similar column decorated with a spiral of relief sculpture was erected in the Place Vendôme in Paris to commemorate his victory at Austerlitz.