The public part of the settlement was located at the top terrace of the hill (today's park). The residential part was located on the slopes coming down towards the foot of the hill, and the foot itself was full of trade and fair facilities.
This Roman public architecture complex consists of a bathing part containing the spa buildings with pools and a basilica, the forum with porches around the main thermal spring, and the capitolium with Jupiter's, Juno's and Minerva's temples.
Because of the specific ground conditions around the thermal spring- travertine deposits- the Roman architecture was well preserved, which makes Aquae Iasae one of the best preserved localities in Croatia.
Thermal sulphur water rising in the park is extremely healing. Its temperature is 58 ̊C, and the evidence indicate that the same spring has been in use for over 2000 years, from the ancient history until today.