Place Guillaume II, popularly known as the Knuedler, is the central square in Luxembourg City, covering an area of more than 9.250 m². Between 2020 and 2023, the square underwent a complete refurbishment, including new paving, new tree planters, a playground, new lighting, a fountain and modernised access to the LCTO tourist office. Architect Arlette Schneiders developed the concept for the Ville de Luxembourg. The work was carried out in seven phases to allow the square’s hospitality businesses and weekly market to continue as much as possible, and was completed in spring 2023.

As part of this refurbishment, the square received new, large plane trees. Van den Berk Nurseries supplied Platanus ×hispanica 'Malburg' with a trunk circumference of 70 to 80 centimetres. Due to the size of the trees and the narrow, historic streets in the city centre, the trees were transported to the centre at night on specially extended transport vehicles under police escort. Existing plane trees that could not return to their original location were replanted elsewhere in the city at the time.

Plane trees tolerate hard surfaces and air pollution well, and their large leaf area captures fine particulate matter. Because of their eventual size, they cannot be planted everywhere in the city centre. This square does have sufficient space: the crowns provide shade across a large part of the square, lower temperatures on warm days and break up the otherwise predominantly paved space with visible greenery.