Emma Willoughby, Lynn Walter and her niece Lucy Mellor strapped into harnesses and lowered themselves off the landmark for the charity.
Emma is acting home manager for Alderwood Care Home, in Salford, and Lynn is senior regional manager for the Hill Care Group, which operates the home.
Together they raised £907 for the fight against dementia.
“I was petrified,” said Emma. “But I’m glad I did it and we raised a great amount for the Alzheimer’s Society.”
Lynn said: “I was really nervous but excited. My young niece Lucy absolutely loved it.
“You couldn’t pick a more picturesque building to abseil from and for a charity so close to the hearts of everyone at Hill Care.”
The Hill Care Group has run a year-long campaign to fundraise for the Alzheimer’s Society. Emma and Lynn’s abseil takes the total to almost £9,500.
Care homes across the north of England have taken part in cake sales, cycle rides, car washes and more to raise funds.
Lynn added: “Many of our homes have specialist dementia care services, which is why Hill Care’s managing director Wendy Waddicor chose the Alzheimer’s Society to focus our fundraising efforts on over the past year.
“I’m delighted the abseil could add such a great amount to an already fantastic total raised by everyone at Hill Care.”