the Praefectura orae maritimae and then in 15 CE annexed to the province of Moesia (later Moesia Inferior), covered 47 hectares in present-day central Varna and had prominent public baths, Thermae, erected in the late 2nd century AD, now the largest Roman remains in Bulgaria (the building was 100 m (328.08 ft) wide, 70 m (229.66 ft) long, and 25 m (82.02 ft) high) and fourth-largest known Roman baths in Europe. Major athletic games were held every five years, possibly attended by Gordian III in 238 CE.
Odessus was an early Christian centre, as testified by ruins of ten early basilicas, a monophysite monastery, and indications that one of the Seventy Disciples, Ampliatus, follower of Saint Andrew (who, according to the Bulgarian Orthodox Church legend, preached in the city in 56 CE), served as bishop there. In 6th-century CE imperial documents, it was referred to as "holiest city," sacratissima civitas. In 442 CE, a peace treaty between Theodosius II and Attila was done at Odessus. In 513, it became a focal point of the Vitalian revolt. In 536, Justinian I made it the seat of the Quaestura exercitus ruled by a prefect of Scythia or quaestor Justinianus and including Lower Moesia, Scythia, Caria, the Aegean Islands and Cyprus; later, the military camp outside Odessus was the seat of another senior Roman commander, magister militum per Thracias. The Jire?ek Line, or the approximate linguistic frontier between Latin and Greek linguistic influence, ran through the Balkans from Odessus to the Adriatic.
Theophanes the Confessor first mentioned the name Varna, as the city came to be known with the Slavic conquest of the Balkans in the 6th�7th century. The name may be older than that; perhaps it derives from Proto-Indo-European root we-r- (water) (see also Varuna), or from Proto-Slavic root varn (black), or from Iranian bar or var (camp, fortress: see also Etymological list of provinces of Bulgaria). According to Theophanes, in 680, Asparukh, the founder of
