The stadium construction began on 21 October 2002 and was officially opened on 30 May 2005. The primary designers are architects Herzog & de Meuron. Allianz Arena is a football stadium in Munich, Bavaria, Germany with a 75, 000 seating capacity. Widely known for its exterior of inflated ETFE plastic panels, it is the first stadium in the world with a full colour changing exterior. Located at 25 Werner-Heisenberg-Allee at the northern edge of Munich's Schwabing-Freimann borough on the Fröttmaning Heath, it is the second-largest arena in Germany behind Signal Iduna Park in Dortmund. The two professional Munich football clubs FC Bayern Munich and TSV 1860 Munich had played their home games at the Allianz Arena since the start of the 2005–06 season. The clubs had previously played their home games at the Munich Olympic Stadium since 1972. 1860 Munich previously had a 50% share in the stadium, but Bayern Munich purchased their shares for €11 million in April 2006. The arrangement allowed 1860 Munich to play at the stadium while retaining no ownership until 2025. However, in July 2017 the rental contract was terminated, making Bayern Munich the sole tenants of the stadium.