Having visited both, (The Olympic Stadium during Euro 88, and The Millenium Stadium for Norwich City's play off final against Birmingham City a couple of seasons ago),I know of one Stadium that is as visually stunning, inside and out, as the Olympic Stadium in Munich.

The Millenium Stadium in Cardiff, Wales. The home of many English domestic cup competitions until the rebuilt Wembley Stadium surpasses it shortly, (all English fans hope anyway! )

With the sliding roof open or closed, the atmosphere is electric.

On the subject of Wembley, 'shuvman' posted a placemark and a website for it back in June. shuvman's Wembley Stadium post