The striking castle ruin-style Fyrish Monument, in Alness, Easter Ross, dates back to the 18th century.
Follies cover a series of eccentric landmarks built by barons, lairds, and royalty between the 16th and 18th centuries.
But locals say the Fyrish Monument will be "dwarfed" by 250m turbines proposed as part of German energy firm RWE's Ceislein Onshore Wind Farm scheme.
The Save Fyrish campaign has published a video online with a visualisation of how the 20 planned wind turbines would tower over the 10.5m tall monument and spoil its "spectacular" hilltop views.
The stone structure was built in 1782 on the orders of General Sir Hector Munro, 8th Laird of Novar.
Munro reportedly hired locals to construct it to provide income for people displaced by the Highland Clearances.
Save Fyrish have launched a petition against the development.
They say: "The turbines would significantly harm the scenic and peaceful environment surrounding ...