Inaugurated in 2020, this slender 137-metre-high tower – the fifth tallest building in the Brussels Region – can be found between the boulevard and the railway, on a cramped plot on the eastern edge of the Northern Quarter.

The idea for its original shape came from one of the owners, who had an inspiration after standing his silver pen vertically on the table: a tower with an ellipse floorplan, wrapped in glass curtains vertically streaked with anodised aluminium sun visor fins or 'outriggers'. This design earned it the name Silver Tower, although that was soon replaced by Iris Tower. Since 2021, it has been home to the headquarters of the Brussels Regional Public Service and the Brussels tax authorities.

Made of 100% concrete and prefabricated elements, the building rose out of the ground in a mere 17 months, thanks to the top-down and bottom-up construction process, which consists of building simultaneously from the top and bottom. It has a total of 40 levels, including 7 underground, and a largely open upper ground floor, featuring zigzagging piles. Bureau Greisch, the consultancy responsible for designing the structure, received an Innovation Award of Excellence from the CTBUH (Council on Tall Buildings and Urban Habitat) for the design of the adaptive outriggers that contribute to the tower's rigidity and flexibility.

On 23 October you will have a chance to visit different parts of the tower. From the 32nd floor, you will also enjoy a 360° panoramic view of the Brussels region and an exhibition of the works of photographer Yannick Coppens will chart the impressive construction of this glass vessel.

Architect: Accarain-Bouillot Architectes Associés / Atelier d'architecture de Genval

Design office: Greisch / Technum