We're surrounded by parking ramps and yet we hardly see them.
In our downtowns, ramps are in the background, usually connected to skyways, and they're often bleak-looking at street level.
Still, they tell a fascinating story of the evolution of engineering and architecture during the past 60 years.
After World War II, the baby boom led to a building boom that launched thousands of suburban developments. Government policies supporting homebuilding and highway construction fueled the growth of car ownership and, logically, increased need for parking.
At the same time, advancements in engineering, accelerated by the demands of the war, transformed the technology, scale and design of parking structures.
For aging downtowns, parking ramps were a godsend. They became a way to hold onto retail customers who had begun to flee to suburban retail malls like Southdale.
By the early 1950s, downtown Minneapolis was building its first modern parking ramps (which got their name from the inclined concrete surfaces that stacked cars up on a small city lot).
The structural design for Downtown Auto Park at 9th Street and LaSalle Avenue was by a Detroit engineering company that invented a new reinforced-concrete construction technique eliminating the need for column capitals, visible beams, drop panels or load-bearing columns on the exterior edges.