At 5:39 a.m. on Wednesday, February 12, 2014, the earth beneath the museum's floor in the Skydome area (located under the spire) of the building gave way, swallowing eight Corvettes in the process. Fortunately, because the museum was closed at the time, there were no injuries.
The cause of the of collapse is the presence of a massive cave that exists underneath the museum – Kentucky, I learned during my visit, is home to a large network of caves – whose roof gave out under the weight (presumably) of the Corvettes.
The cave, estimated to be thousands of years old, created a sinkhole in the museum's floor that measured 18.3 metres (60 feet) by 13.7 metres (45 feet) wide and 9.1 metres (30 feet) deep.
Museum staff spent the next two years repairing the hole by filling it in with 3,607.85 metric tonnes of crushed limestone and reinforcing it with 46 micropiles (steel columns) that measure 12.7 – 17.8 cm (5 – 7 inches) in diameter.
A structurally-reinforced concrete slab floor was laid down on top, but staff also saw fit to include a 1.21-metre square (48-inch) manhole that provides access to the cave which, by the way, is about 60.96 metres long (200 feet) and 15.2 metres (50 feet) wide in some areas. The repaired Skydome area, along with the attendant exhibit documenting the incident, opened on February 12, 2016, exactly two years after the collapse.