Principality Stadium

Principality Stadium in Cardiff, Wales, boasts a massive all-seater capacity of 74,500. It is the national stadium of the Wales national rugby union team and frequently hosts major football finals and boxing matches.

The stadium officially opened its doors in June 1999 to host that year's Rugby World Cup. At the time of its completion, it was the second stadium in Europe to feature a fully retractable roof.

The venue was famously named the Millennium Stadium from its opening until 2016. The name was officially changed to Principality Stadium after securing a lucrative 10-year naming rights partnership with the Principality Building Society.

Yes, the stadium features a massive, mechanized retractable roof that takes roughly 20 minutes to fully close. When closed, it completely covers the seating bowl, creating an incredibly loud and intimidating atmosphere for indoor sporting events.