Watch List notes:

The Roman Empire
Trajan, 98 – 117

Sestertius 2nd half 107-110, Æ 27.12 g. IMP CAES NERVAE TRAIANO AVG GER DAC P M TR P COS V P P Laureate head r., drapery on l. shoulder. Rev. S P Q R OPTIMO PRINCIPI Two-storied, arched bridge over river indicated by waves; each storey is divided into eight compartments; at either side, gate with steps surmounted by statues; boat attached near the gate on the r. In exergue, S C. C 542. BMC 847. Strack 385. Hill, UC 136, 251. KOSH pl. 69, 261. CBN 315. Woytek 314bC. RIC 569.
Rare and in superb condition for this difficult and interesting issue. Brown
patina very gently smoothed in field, otherwise extremely fine

Ex M&M 76, 19 November 1991, 875 and M&M 92, 2002, 72 sales.
The identity of the bridge depicted on the aes of Trajan has long been a subject of debate. It is often called – at least colloquially – the 'Danube Bridge' as a reflection of the effort by the Romans to span the Danube at Drobeta in Romania during their campaign against the Dacians. If the single-span, stone bridge on this sestertius is meant to represent the one over the Danube, it is merely symbolic, for one that Trajan built had perhaps twenty arches and was made of wood. Military pontoon bridges are well represented in surviving works of art, including on columns erected by Trajan and Marcus Aurelius, and on coins of Marcus Aurelius and Caracalla, all of which show utilitarian structures and the boats that supported them. The bridge on Trajan's aes appears to be distinctly urban and civilian in purpose, being decorated at the ends with tower entries and fitted with a roof over the span. Furthermore, the representations of pontoon bridges all show them as soldiers are crossing. A bridge similar to Trajan's appears on coins of Septimius Severus, and it, too, defies precise identification. Indeed, it is possible – even likely – that both are symbolic, with Trajan's representing his bridge over the Danube and Severus' being an allusion to crossings in the war the Severans waged against the Caledonians