Rome: Engineering and Empire Crossword

This made Roman concrete waterproof and strong.
Emperor who is suspected of burning 10 of Rome's 14 regions to clear way for his own palace.
Architectual feature that allows for strength in building, while using fewer materials.
One in every____________ Romans were slaves.
Vespasian drained Nero's artificial lake, and built this building in its place.
Assassinated by members of the Roman senate.
How Caesar's soldiers crossed the Rhine river into Germany.
Rome's first international highway.
Large structures that brought water into Roman cities.
How did Nero die?
The term for the men who fought and died for entertainment.