Taking the fist-kiss-brief literally my first idea would be to create a walkable installation in front of the industrial building on the Tillebierg.
As a contrast to the closed and rather repellent building in the background it should be a very open structure that provides different niches for groups of people gathering – a public place still offering a certain degree of privacy and intimacy.
The structure could resemble two figures hugging to symbolize the “get together” character of the installation.
The different “cabins” should be oriented toward specific views on Differdange.
Citizens of Differdange could be invited to paint the insides of the “cabines” to give each of them an individual character.