Los Angeles's Four Level Interchange: A History of Cities in 50 Buildings

April 13, 2015
Planned as ‘a landmark of beauty and pride for the entire city’, the Stack was the first of its kind, helping to create LA as a freeway metropolis and condemning its residents to largely car-dependent lives

The most famous – and most infamous – buildings in Los Angeles aren’t buildings. No one lives or works in them, but they have had an extraordinary impact on the city, its people, and the world as a whole. LA’s most important buildings are its freeways, and the most iconic piece of this vast network is the Four Level Interchange: an elegant vertical boating knot of freeways and ramps just outside downtown.

The Four Level, or Stack as it’s sometimes known, was the first interchange of its kind when it fully opened in 1953. Diverging from the common looping cloverleaf design of other freeway intersections being built around the country early on in the interstate highway system, the Four Level was relatively compact and, as the name implies, built in overlapping layers. The idea for the space-saving stacked interchange is attributed to WH Irish, a location engineer with the California Division of Highways in the 1940s. His idea has since been replicated in cities across the US and the world.