Alexander Byers made his fortune in iron piping and had a huge home designed with two separate wings. Like any proper robber baron of the era, he had his mansion built along Ridge Avenue's "Millionaires Row" in 1898 in Allegheny City (now part of Pittsburgh's Allegheny West neighborhood).
He, his wife and their children occupied one side, while his daughter Maude and her husband, John Lyon, and their children lived on the other. Maude was a social activist of the times, and often left her kids in the care of a nanny while out doing good, which irked her dad no end. A woman's place and all that...
In 1902, Byer's 4-year old granddaughter died when she crawled atop a skylight and fell to her death when the glass broke, as her German nanny napped. The next day, the nanny hung herself from the stairwell.
It's said in one version of the tale that the ghost of the little girl watched her as she swung above the steps, witnessed when the body was discovered.
Before she tied the noose, she wrote “Please don't blame me” in the dust on the stairwell (apparently the cleaning lady was no more conscientious than the nanny.)
Byers never spoke to his daughter after that, of course blaming Maude for leaving the child in the care of a nanny instead of watching her herself. There had been many sightings of the girl since and the sounds of her crying (though none of Byers, who is probably still humbugging Maude in the netherworld).
The nanny has also been spotted, running up the stairs or walking hand-in-hand with the little girl. Sometimes the "thud" of her falling body can be heard. And every time the house is cleaned, the nanny's message is seen again, scrawled in the dust.
The 90-room manse is now Byers Hall, serving as Community College of Allegheny County's student union building and administrative offices. When CCAC removed the skylight in 1990, sightings of the granddaughter ceased. But the nanny is still around, serving an eternal penance for one brief moment of inattention.