The thousand-year-old history of Plovdiv is exuberant and unique. The culture layer of this town is a real phenomenon that includes remnants of human civilizations. Life here has been going on for more than eight milleniums and for that reason Plovdiv is called 'an everlasting' city. It can be only compared to Athenes and Rome because it is a centre of unique Thracian culture just what Athenes and Rome are for the ancient Greek and Roman civilizations. The monumental architectural complexes that were revealed in Philippopol, the strong fortification system, the grand engineering facilities, the splendid mosaic floorings in the residential and public buildings, all they confirm our notion of Philippopol as the biggest, most brilliant and most beautiful city on the river Hebar.
In 342 BC, the troops of Philip II of Macedon established their domination over Thrace. The renaming of Eumolpia to Philippopolis was an act with which the conqueror Philip II of Macedon declared the annexing of the conquered lands to the Macedonian state.
Archaeological studies of the layer from the Hellenistic Age of Philippopolis show that the urbanisation processes characteristic of all conquered cities took place there as well. The Hippodamos city planning system began to be introduced gradually. A characteristic principle of the orthogonal plan was the crossing at a right angle of the main and secondary streets - cardo and decumanus, oriented to the four directions of the world, and the building of the areas formed -insulae. The culmination in the ambitious building programme came with the construction of a new fortification system. The newly-built solid fortification walls transformed Trimontium into a strong fortress. Sectors from the earliest fortification system can be seen preserved today on the territory of the initial city nucleus.
The inclusion of Eumolpia in the confines of the Macedonian state necessitated the next - second - reorganisation of the sanctuary on Nebet Tepe Hill. The temples and the round platforms from the western terrace of Nebet Tepe Hill were no longer used and were destroyed by the new fortification wall. The eastern terrace was added to the sacred territory. A pit sanctuary spread over the two terraces.
During that period, the necropolises were in immediate proximity to the city territory, to the north. The discovered burials contain incredibly rich funerary offerings. These necropolises are yet another proof of the wealth of the Thracian aristocracy from Philippopolis.
THE ROMAN PERIOD
In 45-46 AD, at the time of Emperor Claudius, Philippopolis was included in the Roman Empire and acquired the name of Trimontium. Within that empire it was the most important urban centre in the Roman province Thracia. At the end of the 3rd century AD, the city became administrative centre of the province. However, the new name Trimontium failed to become popular and the city preserved its old name, Philippopolis.
The ruins of Trimontium are found at a depth of 4 to 7 m below the level of the modern city.
Due to frequent attacks by barbarian tribes at the time of Emperor Marcus Aurelius, the parts of Trimontium fortified earlier were incorporated in a common defence system consisting of two rings with the city built in the plain. The event was commemorated with an inscription in Greek and Latin, placed by the authorities at the entrance to the city, near the northeastern gate. Not far from the gate there was a triumphal-memorial ensemble dedicated to the family of Emperor Marcus Aurelius,
The external fortification wall was substantially damaged by the invasion of the Goths in 251 AD, and the city was burned down and destroyed. Later the city was protected again by strengthening the fortification walls with new towers.
At the time of Roman domination, the process of the introduction of the orthogonal system was completed. The entire built-in area of the city was crossed by streets paved with large slab-like stones, with water pipelines and sewage system. A grandiose water supply construction -an aqueduct - was built in order to supply the city with drinking water from the Rhodope springs. The total length of the construction in the territory outside the city is nearly 30 km. The aqueduct was elevated 6-8 m above the ground by means of massive vaults, 4 m in diameter.
The real central part of the modern city coincides fully in terms of urban planning with the:; central part of the city during its Roman Age. This is proven by two major public architectural ensembles discovered by archaeologists in the heart of the present-day: Plovdiv: the ancient Forum and the Odeon.