Oescus, Palatiolon or Palatiolum (, ) was an important ancient city on the Danube river in Roman Moesia. It later became known as Ulpia Oescus. It lay northwest of the modern Bulgarian city of Pleven, near the village of Gigen. For a short time it was linked by the longest and most famous stone bridge across the Danube, Constantine's Bridge, with the ancient city of Sucidava (modern-day Corabia, Romania). The city seems to have at one point reached a area of 280,000 m2 and a population of 100,000. Archaeological excavations have brought to light parts of the ancient city and are continuing. Etymology The name of the Roman town comes from the river Oescus (today Iskar). It probably meant "water" in the local Thracian dialect. History The Greek geographer Claudius Ptolemy (ca. 90–168 AD) described Ulpia Oescus as a city of the Triballi, an independent ancient tribe which inhabited today’s northwestern Bulgaria. Under Roman rule, Oescus began as an important military base and legionary fortress as part of the Danubian Limes. Together with the adjacent settlement, it developed into a city. It was connected to the rest of the Roman empire by three important roads: linking the Via Egnatia to the Danube: from Heraclea Lyncestis to Ceramiae, Stobi, Astibos, Tranupara, Pautalia, Aelea, Serdica, Oescus. from Philippopolis to Oescus: Philippopolis ‐ Viamata (Voynyagovo‐"Gorni Stenici") – Sub Radice (Hristo Danovo) – Montemno (Beklemeto‐"Karcovija Buk") – Ad Radices (Beli Osăm/Kamen Most) – Sostra (Lomec) – Melta (Loveč) – Doriones – Storgosia (Pleven) – Ad Putea (Riben) – Oescus along the Danube: Singidunum (Belgrade) – Viminacium (Costolac) – Ratiaria – Oescus – Novae (Steklen by Svistov) – Durostorum (Silistra) – mouth of the Danube River. The Roman Legio V Macedonica (Fifth Macedonian Legion) maintained its permanent military fortress intermittently at this site from 10 to 101 AD. In 62 the legion left to take part in the Nero's Parthian War in Armenia and was later sent to the east to fight in the conclusion of the war. It also fought in the Jewish-Roman War in 66–67. After a short stay in Alexandria in Egypt, this legion returned to Oescus in 71. During its absence, the camp in Oescus was probably occupied by cohors IV Gallorum equitata. When the Danube defences were strengthened a second legion (Legio IV Scythica) was also stationed here until 101 AD. Between 106 and 112 Trajan granted the city the