The central part of the Theatre’s cavea appears to be built out of the rock itself, thus taking full advantage of its position on one of the town’s highest hills, while the sides are supported in vaulted galleries. It can hold up to 6,000 spectators, and is constructed of three horizontal sectors (moeniana) which are subsequently divided by five radial stairways in the ima, and seven in the media and summa cavea.

The main public access was made through two side corridors (aditus) over which rested lintels dedicated to Lucio Caesar (on the eastern side) and probably, Caio Caesar (on the western side).  Both dedications, together with the inscription “consul designatus en el cursus de Caio” on one of the coins found in the hyposcaenium pit, indicates that the building was most probably in use between 5 and 1 B.C.

These side corridors also allowed access to the orchestra: this semicircular space in front of the stage or proscaenium contains three rows of seats (proedria) reserved for important members of the public.  The proscaenium itself, where the actors appeared together with the choir, extends to a length of 43.60 m. The stage was finished at the front with jointed segments by means of exedrae, under which there was a vaulted drain to remove rainwater, with three central drains connected to two channels located at the ends of the circulation duct, at the foot of the ima cavea.

From the analysis of the residual impressions and architectural remains, the scaenae frons or stage façade was located opposite the stands.  It had a floor joined by three curved exedrae with elevations of 14.60 m. in height and two fronts, in which the combination of the reddish tones of the columns, the white of the capitals and bases and the grey of the podium and entablature will display an impressive play of colours.

At the back, the porticus post scaenam, rose in terraces culminating in a double porticoed gallery surrounding a central garden.

The building quickly became an essential part of the old town’s landscape.  The quality of its materials; its bases, its cornices and especially its capitals, demonstrate the importance of the building, and along with its rich ornamental programme, makes the Theatre of Cartagena a magnificent example of the public and monumental architecture during the Augustinian period in Hispania.

Numerous ideological messages are highlighted in this decorative programme, including the introduction of cults to the traditional divinities of the Roman State, identified by three altars where the symbols of the Capitolina Triada,  are represented.