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
Contemporary architects are, however, increasingly engaging with ornamentation. The zenith was Grayson Perry and Charles Holland of FAT’s fairytale House for Essex (p64), but it does not serve as an indicator because the involvement of an artist has allowed an enhanced engagement with ornament until it surpasses mere decoration and becomes embodied in the architecture in a way that architects do not allow themselves to do. Think of FAT’s old work: the ornament is all contained within a surface - a facade - which allowed them to separate out the (Modernist) architecture from the (kitsch) superficiality of the elevation. Like Venturi before them, their ornament allowed them to have their ornamentally iced cake - and eat the Minimal Modernist sponge underneath.