One of the most unusual Roman sites in Tunisia, Bulla Regia lies about 70 kilometres south of Tabarka and is well worth the drive. What makes it extraordinary is that the wealthy inhabitants built their houses downwards — the upper floors were conventional, but below ground they created spacious, well-lit rooms to escape the summer heat.
Several of these underground villas are open to visitors, and the mosaic floors survive in remarkable condition. The site is much less visited than Dougga or Carthage, which means you can often explore at leisure. The small on-site museum displays the finest mosaic panels found here. Allow two to three hours.