A road side fence/partition in front of Siberia Restaurant in Saariselkä, Lapland Finland. The partition is made of coloured planks, which when seen from a certain distance/angle on the approach road displays a continuous band of rainbow spectrum colours - Violet, Indigo, Blue, Green, Yellow, Orange and Red aka VIBGYOR. I think such a work is called Anamorphic Art. To really appreciate it, it has to be seen in Google Street View.