America is not unique in having desolate shopping malls, but the sheer number of underperforming, closed, and abandoned malls should give cause for alarm—including the mammoth Century III Mall near Pittsburgh, Pennsylvania.

First appearing en mass in the middle of the 20th century, enclosed malls helped define development patterns in the United States for over six decades with sprawling suburban tracts taking root in place of dense cities. The land was plentiful and cheap, luring not only residents but commercial developers who saw potential with indoor malls surrounded by acres of free parking. The airy and stylish centers offered air-conditioned comfort and amenities that were not found in downtowns that were increasingly seen as downtrodden and outdated. For decades, these malls were refreshed, rebranded, rebuilt, and replaced at a furious pace, with nearly every metropolitan area ringed with one or more malls, killing off retailing in the center city.

But something happened towards the beginning of the 21st century—traditional indoor malls became unfashionable. Construction of new enclosed centers slowed as outdoor shopping centers and downtown revitalization began to take root across America. Many outdoor malls were patterned after their indoor companions, consisting of the same mix of mid-range stores and anchors, while others were more elaborate with shops, restaurants, bars, residences, and offices intermixed. These new centers had no concourses to cool and heat and often incorporated elaborate landscaping and water features to draw in shoppers and tourists.

Malls once depended upon former bellwethers such as Sears, Montgomery Ward, Service Merchandise, and Best, but many of those chains either disappeared by declaring bankruptcy or by merging with a more profitable company. Other once-prominent retailers, like Macy’s and Barnes & Noble, are closing stores because of a lack of product differentiation and the rise of online retailers.

The resurgence of the city center has also had a profound impact on shopping. Independent retailers and chains have taken hold in many urban areas that were once barren of shopping for decades, lured in by 18-to-35-year-olds that have repopulated neighborhoods once forgotten and left behind for suburbia. What was once concentrated to the largest cities in America, like New York and San Fransisco has spread to areas in the rust-belt and sun-belt, like Cincinnati, Detroit, Pittsburgh, Charlotte, and Birmingham.

These factors have all played into the demise of Century III Mall.

Horne’s, one of Century III’s original department stores, was acquired by Federated Department Stores and became a Kauffman’s Furniture Gallery and then Macy’s Furniture Gallery when the Kauffman’s name was retired by Federated. The Kauffman’s department store, a local chain, became a Macy’s for the same reason, a move that was much resented by locals.

Gimbels, another original anchor, closed in 1986 because of the chain’s slow decline. It was replaced by a succession of chains, including T.J. Maxx, Marshall’s, Wickes Furniture, Steve & Barry’s, and Dick’s Sporting Goods. Of those, Steve & Barry’s was closed due to bankruptcy; others, like T.J. Maxx and Marshall’s, closed because of underperformance.

Sears, the last department store to open at Century III, became the latest anchor to flee Century III. What was once one of the nation’s most prominent and successful chains has become a farce and under-performer in nearly every measurable aspect.

Without successful, stable anchor stores, Century III became highly dependent on its inline retailers for vitality, only to see foot traffic disappear. The mall saw further decline with the arrival of newer mixed-use developments elsewhere in the city, including The Waterfront in Homestead and SouthSide Works in the South Side Flats neighborhood. More recently, Century III was sold to Moonbeam Capital Investments for a mere $10.5 million. What happens to the increasingly ailing mall remains to be seen.