This is the main Roman display area, and you can walk through all the Roman structures here. This is one of several display areas at Lunaria Emporium at ground level surrounding the main store. Each area has a theme and has its own EEP sky setting to accentuate it. Make sure you have Shared Environment selected as well as higher graphics to see the shadows and materials.
You can reach this area by clicking the Roman sign in the lobby on the left side, or by taking the bridge, hopping a boat, or flying.