By the second half of the 2nd century, Londinium had many large, well-equipped stone buildings, some of which were richly adorned with wall paintings and floor mosaics, and had subfloor hypocausts. The Roman house at Billingsgate was built next to the waterfront and had its own bath. In addition to such structures reducing the city's building density, however, Londinium also seems to have shrunk in both size and population in the second half of the 2nd century. The cause is uncertain but plague is considered likely, as the Antonine Plague is recorded decimating other areas of Western Europe between 165 and 190. The end of imperial expansion in Britain after Hadrian's decision to build his wall may have also damaged the city's economy.