The town was founded in the first century A.D. by the Roman legions which had occupied the region they called Pannonia, and which is today's Transdanubia. The military settlement was situated on the site of today's Óbuda, to the south of Árpád Bridge. Aquincum was a civilian town surrounded by walls, with aqueducts, sewers and paved streets. Artisans, tradesmen and vine-growers lived here, but in the fourth century the repeated attacks of the Barbarians forced the population to leave the city. Gradually even the walls disappeared; the foundations came to light only during excavations which, though started at the end of the eighteenth century, have only recently become regular and continuous.
The entrance to the field of ruins is near the railway line. The first important monument there is the remains of the basilica of the Forum. Beyond the east-west main road vast public baths have been unearthed. We can recognise the cashier's booth, the dressing-rooms and further on the cold, lukewarm and hot-water pools. The heating system was installed under the floor which was supported by columns and in the passages of the hollow walls. The baths were fed by a medicinal spring. Nearby stood the great markethall, and to the east the main part of another bath , a swimming pool 6 by 4.5 metres (21 by 15 ft.) in area, and next to it a large Roman-style dwelling-house, with rooms opening out from a colonnaded courtyard. The owner must have been a rich man, because the house had a separate main building, the mosaic floor of which, depicting wrestlers, can be seen today under a protective covering. Behind the mosaic-decorated baths the cave-like Mithras temple is worth seeing. The cult of Mithras, the light-god of the people of the Near East, was widespread in Pannonia.
In the halls of the museum the most precious finds unearthed during the excavations are displayed. In hall 1 a map shows the location of Pannonia within the Roman Empire and that of Aquincum in the province of Pannonia. The carved stones exhibited are remains of altars and statues of gods. In hall 2 to the right, interesting items are the terra sigillata vessels and bronze statuettes that found their way to Pannonia from different parts of the Empire. These items include a lovely bronze representing a black slave-boy. The instruments put on display were used by Roman land surveyors and builders of roads. Hall 3 is reserved for the relics of handicrafts and trade. Notable among these are a wooden casket that have come down to us intact and a potter's kiln. Hall 4 (to the left) contains the mementoes of art and cultural life. Unique among the objects to be seen here is a water organ. Religious life in the Roman period is presented in hall 5. Here mention should be made of an altar dedicated to Mithras which has survived intact, and of the cultic objects of the early Christians.
The civilian amphitheatre stood on the other side of today's railway line; the 53-metre (58 yds.) long elliptical arena could hold 5,000 to 6,000 spectators. On the way back from Aquincum you will find it worth while to stop and have a look at the ruins of the amphitheatre of the military town, in Nagyszombat utca, a side-turning off the main road. Built in the second century, this in one of the largest amphitheatres built by the Romans outside Italy; the length of the arena is 89 metres (98 yds.); it could hold an audience of 13,000. On the side facing the hills, the original height and the shape of the cages where the wild beasts were held are perceptible, thanks to recent reconstruction. Another significant monument of this period in Óbuda are the Roman military baths under the house at No. 3 Flórián tér, with their heating area still intact and their cold and hot-water pools. Not far from here, on the corner of Meggyfa utca and Vihar utca, can be found in the courtyard of a school building the most beautiful intact mosaic floor in Pannonia: made by an Italian master from extremely fine marble grains, it depicts a scene of the Hercules myth.
Though not containing any Roman finds, the De- partment of Modern History of the Budapest History Museum, known also as Kiscelli Museum should be mentioned here as it is also in Óbuda. It presents the history of the capital, and its Baroque building, a former monastery, is in itself worth seeing.