The Mark Twain Library in Detroit opened in 1940 and served as an important community hub for decades, hosting events and providing a safe space for neighbourhood children. However, as the surrounding area declined in the 1990s, the library's finances deteriorated and it was forced to close and then only open two days a week. It eventually shut down permanently due to disrepair and asbestos issues.
Despite community fundraising efforts, plans to renovate the library were never realized. With no progress being made, the city demolished the building in 2011, much to the anger of neighbours who felt misled about how renovation funds would be used.
The site where the Mark Twain Library once stood at the junction of Gratiot Avenue and Seneca Street is now an empty lot.
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I didn't mean to imply it was the only problem, but I'd argue it was the biggest which the others stemmed from. Detroit grew around them but as you pointed out it wasn't only when they left that problems happened.