A semi-permanent set of Stonehenge (wiki) replicas (unlike the cupcake version I once made with kids):
Carhenge is located near the city of Alliance, Nebraska, on the High Plains region of the United States. It consist of 39 vintage American cars arranged in a circle and partially buried to keep them upright. Arches were created by welding more cars atop the erect ones. The entire structure is spray painted with a shade of gray to mimic the color of stone. The idea was conceived in 1987 by Jim Reinders as a memorial to his father.
Foamhenge is a full size replica built of Styrofoam and locatred in the town of Natural Bridge, in Virginia, USA. Its creator, Mark Cline, took great pains to shape each 'stone' to its original shape, fact-checking his designs and measurements with the man who gives tours of Stonehenge in England. Each block is set into a hole in the ground, reinforced by a steel pipe that goes through the block. The pipe is anchored to the ground with cement. Each stone is placed in astronomically correct position.
Fridgehenge was a Stonehenge replica built of refrigerators. Fridgehenge stood outside Santa Fe, New Mexico for almost a decade, but following complaints from neighbors, it was dismantled in 2007. Another Fridgehenge was built in the UK in 2014, and yet another one earlier this year.