The 1937 Azerbaijani novel Ali and Nino tells the story of a Muslim man and a Christian woman in the city of Baku who fall in love. Their cultures will not tolerate such a relationship and they are torn asunder. This enormous sculpture in Batumi, Georgia by Tamara Kvesitadze tells their story. Every evening at 7 o'clock, the two lovers approach, kiss, then pass right through each other.
This video shows the sequence. The metal plates forming the bodies don't collide because they are set at alternating heights. You can see more photos at My Modern Met.