re: what do you think was lost in the burning of the library of Alexandria?

The "blueprints" to nearly every grand building in antiquity, advanced knowledge of metallurgy that died with the Romans and wouldn't be rediscovered for 1000 years, countless plays and works of fiction, the history of hundreds of civilizations lost to time, knowledge of medicine and the workings of the human body, the blueprints for the world's first steam engine, the prints for the world's first mechanical calculator (the antikythera mechanism), knowledge of construction techniques, ect. The written copies of all of that was lost in the fire. That meant that when the Roman Empire collapsed, that knowledge died with it.