The recent reconstruction of the HDI Arena (formerly known as Niedersachsenstadion) in Hanover, Germany, was a significant project costing around €82.8 million. The primary goal of this reconstruction, completed in time for the 2006 FIFA World Cup, was to modernize the stadium extensively, both in terms of structure and functionality.

In terms of architectural upgrades, the most notable change was the installation of a new roof. This lightweight, partly transparent roof spans approximately 26,000 square meters and features a unique asymmetrical design, allowing more natural light to reach the pitch. The structure uses a combination of steel rings and transparent membranes, optimizing conditions for the natural grass turf below.

On the exterior, the design is both functional and aesthetically appealing. The glass and steel facade gives the arena a sleek, modern look, blending well with the surrounding greenery and nearby water bodies like the Leine River and Maschsee Lake. Additionally, various technological improvements, including digital payment systems, were implemented, enhancing the overall fan experience.

In summary, the reconstruction did not just focus on the appearance but also introduced substantial functional upgrades, making it a state-of-the-art venue for both fans and players.