Camp Nou

What is it: It's a football stadium that holds 99,354 people, making it the second largest football stadium in the world (the largest is in North Korea). It opened in 1957 and is home to FC Barcelona. 
What's it like: The club's motto is "Més que un club" (more than a club) and the ground does indeed feel like more than a stadium - it's home to thousands of Barca fans. 
Where: Barcelona, Spain  
When: June 2014
How: We got a hop-on/hop-off bus out to Camp Nou from the city centre. We had booked tickets for the tour in advance. We had also been to Sagrada Familia.
Worth noting: There's a nice terrace overlooking the pitch for drinks after your tour. 
Place in the 2015 edition: 470
Did it deserve to lose its place in the top 500: No. If you had to pick one stadium for the top 500, Camp Nou would probably be it.