For 120 years, the Rubjerg Knude lighthouse has been perched on a sand dune on the northern Danish coast, but coastal erosion from North Sea winds threatened to topple it into the sea.
Now the 720-tonne structure has been saved, in an operation to lift it up and move it 70m (230ft) inland "like skates on rails".
Within hours, the lighthouse was transported to its new position.
Local builder Kjeld Petersen said the move would be over by mid-afternoon.
"We could not go faster than 12m an hour because they needed to calibrate the hydraulics. It's in sand and you need to ensure it runs well on the two rails," explained Mette Ring, from the local authority.
The engineers had assumed the lighthouse weighed up to 1,000 tonnes but discovered as they lifted it on Tuesday that it was a mere 720 tonnes and therefore a little easier to move.