To build a folly is essentially to do something a second time, something at an inopportune moment. That something is always the memory of something forgotten, about which we can paradoxically say "There it is again."
Follies were misunderstood, purposeless constructions. They were often only small, extravagant gestures in a garden, easily whisking off the imagination to distant lands, a sort of time capsule built to awaken the memory and induce surprise in passers-by. They marked locations, organized secondary paths in a park, or simply predicted the arrival of better times—a demarcation, a sacred spot, a mysterious trail, a hill whose tragic rocky nature begged for a tower, a party, or the arrival of summer.
“It is demonstrably true that things cannot be other than as they are. For, everything having been made for a purpose, everything is necessarily for the best purpose.” — Professor Pangloss
Folly at Hagley Hall, Hereford and Worcester, built by Sanderson Miller, 1749–50
In architecture, a folly is a costly, generally nonfunctional building that was erected to enhance a natural landscape. Follies first gained popularity in England, and they were particularly in vogue during the 18th and early 19th centuries, when landscape design was dominated by the tenets of Romanticism. Thus, depending on the designer’s or owner’s tastes, a folly might be constructed to resemble a medieval tower, a ruined castle overgrown with vines, or a crumbling Classical temple complete with fallen, eroded columns.