Arcs d'Ellipses (my photo) was an installation by Swiss artist Felice Varini, put up in October 2017 as part of the High Tide Biennale, whatever that is. It was originally meant to be taken down (I believe) in January 2018, but was attracting the attention of a lot of visitors, and the authorities left it for so long that it turned out to be impossible to remove without damaging the surfaces of the buildings to which it was attached. In January 2019 it is very slowly being removed by a contractor, at an expense greater than the amount paid to the artist for his work.
The lines on the roadway were simply painted, but those on the buildings were formed by the attachment of adhesive aluminium foil, which, when pulled off, tended to remove paint or whatever else was on the facades.
At least one property owner says he is taking the council to court.
Felice Varini's website
Wikipedia page
Roel Loopers' blog - with several articles about this matter
Garry Gillard | New: 24 January, 2019 | Now: 17 September, 2020