A 19th Century viaduct in Cornwall is to be closed for two weeks for an in-depth assessment and structural survey, Cornwall Council says.
The survey on the Treffry Viaduct in the Luxulyan Valley, from 4 January, will be part of work to secure the long-term prospects of the landmark.
Cornwall Council owns the viaduct with the Cornwall Heritage Trust.
The council said information gathered from the study would be used as part of bids for funding to preserve the area.
While the work is being carried out, walkers will not have access to some nearby footpaths, the council said.
The granite viaduct, near St Austell, was built by Cornish engineer Joseph Thomas Treffry to provide a horse-drawn tramway link to carry copper, china clay and granite from his nearby mines and quarries.
It is 89ft (27m) high and 650ft (198m) long, with each of its 10 arches having a span of 40ft (14m) feet.
The scheduled monument last carried mineral traffic in the 1930s.