The site was at the junction of the Iatrus (Yantra) and the Rositsa rivers, where the Roman army under Emperor Trajan had been amassed in readiness for the attack in the winter of 101–2 to the Roxolani tribe from north of the Danube and who were allied to the Dacians.

The monumental character of the city however dates mainly to Hadrian and Antoninus Pius (138–161) and inscriptions found are no earlier than 136 when the name Ulpia Nicopolis ad Istrum was in use.

[citation needed] In 198 CE, Septimius Severus and Caracalla sent a letter to the city, thanking its leaders and inhabitants for their festival celebrating the emperors' victory over the Parthians and for sending a substantial monetary gift.

[10] However from about 212 the honorary title Ulpia was no longer used in public inscriptions which is believed to be a result of Caracalla's displeasure with the city[11] after his visit there in 211–212.

[citation needed] In 250 near the city, emperor Decius defeated the Goths under Cniva at the Battle of Nicopolis ad Istrum.

Under Constantine from 306 the damaged northern agora buildings were replaced by two built with opus mixtum masonry, divided into three aisles by rows of large pillars, which may well have been horrea (warehouses), given that other nearby cities (e.g. Tropaeum and Zaldapa) also received horrea rather than basilicas in the same period.

In the 4th century, the Gothic bishop, missionary and translator Ulfilas (Wulfila) obtained permission from Emperor Constantius II to immigrate with his flock of converts to Moesia and settle near Nicopolis ad Istrum in 347–348.

The city also had a three-nave basilica, a bouleuterion, a temple of Cybele, a small odeon, thermae (public baths) as well as a unique Roman building inscribed with termoperiatos, a heated building with shops and enclosed space for walks and business meetings.

A unique public building, a thermoperipatos, has been identified only in Nicopolis ad Istrum so far, out of all cities in Roman Empire.

In 2015 remains of a huge building were revealed which was probably the residence of the agoranomus or curule aedile, a public officer in charge of trade and market operations in Ancient Greek and Roman cities.

[26] The obelisk of Quintus Julius, an aristocrat from Nicopolis, still stands to a height of 14m in the countryside near Lesicheri, about 12 km west of the city.

In 2018, archaeologists found an altar dedicated to the goddess Tyche at a small square in the southwestern corner of the Forum complex, with an inscription in Ancient Greek which is a modified epigram by Demosthenes.