As a city grows, so too does it's need for an ever expanding grid of infrastructure. Power, water, sewage, storm water, and telephone grids must be constantly updated and expanded as the city adds building after building. Oftentimes, old storm drains that are incapable of meeting the drainage needs of an area and flood every time it rains are simply ripped up, and a bigger drain is built and buried again. But what do you do if the storm drain in question was underneath main street of your city's bustling downtown? You can't close down Main Street for several months to replace a storm drain, it would cause utter chaos and traffic jams all over the city. So you let it sit, and every so often make it longer to carry the water farther and farther away. And the longer time goes on, the bigger downtown gets, and the smaller the chance the old storm drain will be replaced before it collapses due to age gets.

However, these drains are few and far between, and often, to get into them you have to pop a manhole in the middle of Main Street traffic. Dallas, Tx, however, has a great exception. Easy to find, easy to get into, and as old as the city itself, hiking into The Rat Race is like walking backwards through history. There are multiple different 'sections' of the drain, all of radically different construction, and each representing a different addition to the system, a different decade, and a different era in history.