The museum stands in the middle of a garden and its style is based on a Roman country villa. The architects tried to give the impression of a reconstruction with their design. Two wings with arched windows on the upper floor are attached to the three-axis central building. Ionic columns stand on either side of the main entrance, supporting the busts of the Roman emperors Marcus Aurelius and Augustus.
The house was severely damaged in both world wars. In 1949 it was provisionally restored and reopened in 1950. However, the conversions did not alleviate the lack of space that arose from the accumulation of finds, because the building remained almost unchanged. The building has (due to the rocky subsoil of the site) no basement and therefore no larger storage rooms available. The federal state of Lower Austria initially only took over the administration on a trustee basis until it finally became state property in 1953. However, the necessary financial means were lacking for an extensive renovation of the building, so that a major conversion and renovation could only be started in 1988. After completion of the conversion measures, the newly designed and extensively modernized museum was able to be opened to visitors again in 1992. The museum is closed until June 2022.