Via Traiana. Just five kilometers downstream from Kladovo and Kostol settlement on the right bank of the Danube, even today there are the remains of 1900 year-old monumental piers of Trajan's bridge. Along with the remains of the bridge there is also a fortress, , Castellum Pontes - Transdrobeta (opposite of Romanian Drobeta / Turnu Severin).
Information about Trajan's bridge, its appearance and technical details have been preserved in some literary sources, with most details coming from Roman writer Dio Cassius (Dio Cassius LXVIII, 13). Among other things, Cassius thoroughly and accurately informed us that it was a stone bridge with 20 piers in the water of incredible height of 150 Roman feet , without foundations (about 45 m), with the space between the peers of 170 Roman feet (about 51 meters).
We have exact knowledge about the appearance of this magnificent bridge from the relief on the two surviving metopes of Trajan's Column, which have been on the Trajan's Forum in Rome since 113.
Even today, on the right, Serbian bank of the Danube (as well as on the Romanian one) one can see a massive quadrangular base foundation with all four piers depicted on Trojan’s column; according to this precise graphic presentation we learned that the peers were connected with built arches, of which the first one, the most massive one, was supporting a vaulted gate portal. The fourth pier, the one closest to the river, with a wide, polygonal platform in its base supported the construction of the first arch of the bridge over the river, which was of a much larger range. Because of its above-ground height of around 10 m (without foundation), with the same persistence, it has successfully stood the test of time for millennia.
And all four preserved piers of the bridge on the right bank, have been well explored within the program of protection measures and archaeological excavations (Djerdap Project), while the underwater piers on the bed of the Danube, their position and level of preservation were examined using a special vessel equipped with sonar (Djerdap Project, 1982).Apart from technical characteristics, it was the first time that the length of the bridge, which amounts to 1069. 664 m, was measured using precise instruments. The poles on the bank were built of stone blocks (opus quadratum , finishing, see Relief bridge on the pier), with the inner core made of quality Roman brick, with strong, stone foundations, with the use of very compact concrete mixture (mortar with many smaller pieces of pebbles, stones ... ) and specially built using wooden box-caissons (cheson). The same (or similar) construction technique was used for piers in the bed of the Danube.
It isn’t known exactly when the bridge stopped being used. The records say that the emperor Hadrian (117-137 AD), Trajan's successor , ordered the demolition of its upper structure to prevent the attacks of barbarians, but it is more likely that this was a temporary measure . It is hard to imagine that it was not in use, at least occasionally in late antique period, during the reigns of Diocletian and Constantine I. The Byzantine historian Procopius ( De aedificiis IV, 6 ) record it that, in his time, in the 6th century, the bridge was in ruins .The remains of Trajan's bridge piers have been conserved and protected from the effects of the Danube lake, by building the defense cofferdam (Djerdap Project). An original copy of Trajan's pier, depicting Trajan's bridge at Kladovo, is exhibited at the Archaeology Museum of Djerdap in Kladovo. From this copy we know what the superstructure of the bridge was like (on the basis of which the first identification and the first reconstruction of the bridge was carried out 300 years ago, see Marsigli). This copy represents a gift of the Italian embassy from 1969, after an exhibition on the city of Rome, held in Belgrade.Trajan's Bridge was the first bridge built on the Danube and a real architectural wonder of the ancient world. Like other Trajan's architectural endeavors in this part of Limes, it was used for preparations for final conquest of Dacia. Trajan entrusted Apollodorus of Damascus, the greatest architect of that time, with the design and construction of the bridge. The bridge was built in just two years, from 103 to 105. Seeing the pillars of the bridge in mid- third century , the Roman consul Dion Cassius wrote that Trajan's Bridge proved that there was nothing that man couldn’t make .A year after the completion of the bridge, Trajan took his legions over the bridge and in 106 defeated king Decebalus which finally made Dacia a Roman province. The wealth of Dacia is evidenced by the fact that as his spoils from it Trajan took 331 tons of silver and 165 tons of gold. His victory was celebrated in Rome and lasted 123 days. 10,000 gladiators took part in gladiatorial combats organized on this occasion and 12,000 animals brought from Africa and Asia were killed.For a thousand years Trajan's bridge was considered the longest bridge ever built. Profile of the bridge was stamped on commemorative coins minted after its completion, and engraved on the famous Trajan's Column in Rome which shows a scene in which Apollodorus hands over the plan of the bridge to Trajan.There are several versions of how long Trajan's bridge was in function. According to one, it was destroyed after only twenty years, by order of Trajan's successor, Emperor Hadrian (117-138); according to another one it collapsed after a few decades, and according to the third one only Emperor Aurelian (270-275) , after the loss of the province of Dacia under the pressure from the Goths, ordered the destruction of the bridge in order to prevent the penetration of barbarian tribes onto the territory of the empire. Of the bridge there remained monumental piers that have long stood the test of time. Twenty piers of Trajan's bridge could be seen even in the nineteenth century, during the low water level of the Danube. In 1906 The International Danube Commission ordered the demolition of two piers that obstructed navigation. The remains of 16 piers were located in 1932, while after the construction of a dam on the Danube in 1982 archaeologists located 12 of them while in the meantime the rest was probably driven away by the water. The remains of the first piers of Trajan's bridge can still be seen on both sides of the river, on the Serbian side, near the village of Kostol, a few kilometers downstream from Kladovo, not far from the remains of a Roman Castellum Pontes built at the same time as the bridge. Recent studies of the remains of Trajan's bridge were made in 2003. There is a project to put a laser holographic projection of Trajan's bridge at the site of the former masterpiece of Roman architecture. That holographic projection would be glowing at night