Around 42 years separate the initial ideas on urban development in Bern-Brünnen and the opening of the Westside leisure and shopping complex. One of the first projects in 1972 fell victim to the "oil crisis"; a second development comprising 6,000 apartments and 4,000 jobs was voted down by the population in 1978. After a series of further projects, the people of Bern approved the perfected, large-scale project for Bern-Brünnen in 2000.

Shortly afterwards, the Migros Aare Cooperative founded the Neue Brunnen AG to make the leisure and shopping complex a reality. In the same year leading architect Daniel Libeskind was commissioned for the project following an international architecture competition. His original, visionary architecture and perfect integration with the surrounding environs was met with both public and expert approval. Construction of the Westside leisure and shopping complex was approved by the canton governor in August 2003. Approval was then granted by the cantonal public works, transport and energy department eight months later and this was confirmed by the cantonal Administrative Court in December 2004. The Administrative Court decision was taken to the Federal Court, which rejected the objections in June 2005.

The ceremonial turning of the first sod in autumn 2005 made it the largest private construction site in Switzerland. Once motorway construction work was completed in spring 2006, Neue Brünnen AG, together with Daniel Libeskind, laid the foundation stone for the Westside leisure and shopping complex on 28 April, 2006. Structural work was completed in September 2007 and most lease contracts with tenants were concluded by February 2008. Work began on the interior in April 2008. The Westside leisure and shopping complex was officially handed over to the public on 8 October, 2008.