The basic shape of the forum has remained the same for centuries. It is a rectangle, close to the shape of a square, with dimensions: 143 m in north-southern direction and 136 m in east-western direction.

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.

The first construction phase marks the beginning of the complex development and bears the plan shape of the urban square.

During the second construction phase the levels of the shops, the ambulatio and the area are raised. Powerful crepido brings the stylobate of columns in Doric order, made ​​of sandstone. The stone drainage leading rainwater away from the roof of the portico kept its original place. The ambulatio is 11 meters wide. The eastern, southern and western sides are formed by four-column Ionic propylaea. 

During the third construction phase the plastic decoration of the complex is replaced. The portico around the area is made of marble. 

The largest number of well-preserved original remains date back to the fourth and final construction phase. Over the existing crepido a new stylobate of syenite blocks is placed. It bears a marble arcade of free-standing columns in the Roman Corinthian order.

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, and remains of an altar with inscriptions, dedicated to the goddesses Demeter and Kore (Persephone).