What happened to Detroit. Over the course of 100 years, the population level of Detroit has rapidly expanded and contracted. And the city infrastructure – streets, schools, hospitals – expanded as well to meet demand. When the population started to decline, the additional infrastructure remained. In many Detroit neighborhoods the amount of houses coming up for sale on the market was far greater than the demand. Vacant houses sat for months and then years, becoming easy targets for arson. Detroit is a city laid out and designed for 2 million people. Less than a third of that number remain today. Detroiturbex.com is a website dedicated to exploring and photographing abandoned buildings in Detroit.