The roof of the former Heeley National School building, which dates back more than 200 years, collapsed on Friday morning.
It comes just a year after conservationists issued a rallying cry calling for the old school to be saved.
The building has since had to undergo a partial demolition and there are fears it will end up being flattened completely.
The story has sparked a lot of debate among Star readers on Facebook and Twitter.
Sean Fogg posted on Facebook: "This is a typical example of why we need to attract investors into the city and work with them.
“Remember they are the ones spending the money to restore Sheffield heritage.”
James Hobson was sad to see the building go to ruin and simply said: “What a shame.”
Annie Bethell tweeted: “When will people learn that buildings need care, protection and mostly investment.
“I will be keeping a keen eye on what happens next.”
Andy Jackson, manager of Heeley Trust, which works to restore disused buildings, fears the roof collapse could signal the death knell for the old school.
He said: “It is really sad but it is an example of what happens if you just leave an old building and don’t look after it.”
The former school building dates back to 1801 and was built on the site of an earlier 18th-century establishment providing education long before it was available to the masses.
It is believed to be the second oldest school building in Sheffield, after a former school in Ecclesfield.
The Star understands there was an attempt a few years ago to secure listed status for the building but this failed because it has been altered internally.
Leaseholder CareTech Community Services said last year that the owner did not have any proposals in place for the building's future.
A spokesman for CareTech said at the time: "At the moment there are no plans for the site, other than to maintain the safety of the building as it is."
We have asked the company for comment and are waiting for a reply.