Fleetwood’s ruined lighthouse, the Wyre Light, has partially collapsed.
A corroded leg at the iconic structure is believed to have given away over the past 24 hours, causing the crumbling landmark, which is 177 years old, to keel over.
Fleetwood Civic Society had been planning a funding bid to carry out urgent repairs, but failed after the lighthouse's owner could not be found.
Chairman Margaret Daniels said: "I'm upset it has happened but not surprised. We have been forecasting it and that's why we were trying to get something done."
Fleetwood Coastguard station officer Mark Sumner said the historic lighthouse has the potential to collapse completely, but added: "It will probably be a nice shape and sight on the horizon for many years to come."
Built in 1839/40 where the Irish Sea meets the River Wyre estuary, the Wyre Light was the first screw pile lighthouse in Britain.
Originally 12m tall, it had a two-storey building for the lighthouse keeper, which was destroyed by a fire in 1948.
The beacon was replaced with an automatic one, and the lighthouse was abandoned in the late 1970s when it was replaced by a lit buoy.
The Civic Society, which said the Wyre Light is of important historic value, said all the organisations they questioned insisted they do not own it.
Likely candidates Wyre Council, Associated British Ports and Trinity House - an organisation which owns many lighthouses in Britain - all said it isn’t them.
The Society also contacted another big land owner in the county, the Duchy of Lancaster,but Margaret said she believed a fear of having to fork out for repair work may have been putting the actual owners off, making them reluctant to come forward.
She said previously: "It is worth pointing out that we would not expect the owner of Wyre light to pay for any repair work.
"We would just need to get permission from them to allow any repair work to be done.
"Without that knowledge, it is unlikely we would get a grant."
A spokesman for Associated British Ports said: "Given the Wyre Light’s extensive 176-year maritime history, ABP is equally interested in fully understanding the ownership history of this important Fleetwood structure."
A Wyre Council spokeswoman said investigations indicated the lighthouse was not part of its property portfolio.
And Trinity House said it had never owned Wyre Light.
There was speculation that Wyre might own the structure because the lighthouse passed into the control from the Duchy of Lancaster to the Board of Fleetwood in the Victorian era.
The Board was the forerunner to the original Fleetwood Council, which then became part of Wyre Council after the major UK-wide municipal changes of 1974.