Outside of Slab City, California lies Leonard Knight's Salvation Mountain, a 150-foot-wide, 50-foot-tall variegated monument dedicated to God. It's like Uncle Owen's home times Pee Wee's Playhouse, with that John 3:16 guy from baseball games* serving as an interior decorator.
After Leonard's balloon refused to fly, he decided to leave the area. Forever trying to promote what was burning so deeply inside of him, Leonard decided to stay one more week to make a "small statement" before he left for wherever his van and his faith would take him. Armed with half of a bag of cement, he fashioned a small monument. One thing turned into another - days turned into weeks and weeks turned into years.
Over the years, Knight has adorned his monument to cosmic love with 100,000+ cans of paint and has expanded it with substances like hay, adobe, tires, and putty. In 1994, the Imperial County government deemed the Mountain an environmentally unsound eyesore and tried to get the structure demolished. Knight successfully fought off government intervention, and Congress recognized the Mountain as a "national treasure" in 2002. Here's a video of Leonard giving a tour of his magnum opus.
*Unlike Knight, who's apparently a pleasant eccentric, the John 3:16 guy is a bit of a goon.