This is completely wrong. The Romans had aqueducts, they could even fill up the Coliseum with water for water shows. The Romans had concrete, and built many b

This is completely wrong. The Romans had aqueducts, they could even fill up the Coliseum with water for water shows. The Romans had concrete, and built many buildings with it. What did Europeans have after the collapse? They went back to building stuff out of wood and brush. Even castles and cathedrals were built of simple blocks, not concrete. When the Empire collapsed, there was a massive loss of institutional knowledge. Specialization of labor completely disappeared: people left the city and their specialized labor jobs to work as feudal serfs. They did this even though Roman law forbade it, because the imperial leadership saw what was happening, but people preferred to go live as serfs so they could eat rather than starve in the city. Name any technology which actually advanced during the Dark Ages. There aren't any. There's a reason it's called the Dark Ages: literacy plummeted and people stopped writing things down.