These remains were discovered during construction work for an underground car park. The renowned architect Hans Hollein was brought in to plan and lay out the site so visitors can see the several levels of architecture dating back almost 2000 years when the city was the Roman garrison town of Vindobona. The whole complex is buried between the Hofburg, Loos House and St. Michael’s Church. Red gravel marks two Roman roads which crossed here and the remains of a wall, floor heating system and building foundations from the seventeenth, eighteenth and nineteenth centuries can be viewed at any time.