The Forum (Agora) of Philippopolis was the commercial, administrative and religious centre of the Ancient city. Meetings, discussions, celebrations and state events were held there. It occupied an area of 20 dca and was situated in the centre of Philippopolis, under the three hills (Trimontium).

Since then the central urban square of Plovdiv has been in the heart of the city.

The forum's shape is a rectangle, almost a square, with dimensions: 100 x 112 m.

A complex of public buildings was built to the North, dominating over the rest of the buildings at the square. It is orientated in east-west. Three entrances, situated along the axes of the eastern, southern and western edge, provide access to the streets, located at the sides of the Forum. The main streets cardo maximus and decumanus maximus intersect outside the eastern entrance of the complex.

In the historical layers of the Forum four main construction phases can be distinguished. They are different in terms of their level, architectural design and use of building materials.

In the northern part of the forum complex are organised the public buildings for the needs of urban governance and other manifestations of urban life. Epigraphic documents recall for the existing of a Treasury. In the northeast corner an Odeon (Bouleuterion) is revealed and to the West of it - the city Library.

At the northern side of the complex some inscriptions, related to the religious and administrative life of the town are found, along with a piece of an invitation card for a performance of gladiator fights. In the area are found pedestals for statues, an exedra – a platform for speeches.