Tenochtitlan in 1519

It was said that when Hernán Cortes first laid eyes on Tenochtitlan, the capital city of the Aztec Empire, he was left speechless. The city had an estimated population of about 250,000, which was somewhere between 150,000-175,000 larger than Spain's largest city at the time, Toledo. Tenochtitlan had broad avenues, probably the largest urban marketplace in the Americas featuring a dizzying variety of foodstuffs and trade goods, and even a zoo. There were barges all along the city's waterfront filled with soil where maize was grown. And then there was the city's stunning temple district, with the Templo Mayor at its center.

Sadly, almost nothing of Tenochtitlan prior to the Spanish invasion survives today. Mexico City would easily be one of the most architecturally impressive cities on earth if just part of the fabled Temple District had survived.

Here's a video (albeit an old one) with accurate 3D recreation of Tenochtitlan's fabled Temple district.It;s nothing short of magnificent.