Most people playing Monopoly (multiple venues)

According to Official Guinness Records,

The largest simultaneous game of Monopoly was achieved with 2,918 people at 21 locations world wide and on a website organised by Hasbro, on 27 August 2008.

For a complete list of 2008 records, please visit 2008 Guinness Records in United Kingdom.

Other United Kingdom records that might interest you:

• Longest marathon playing camogie
• Youngest footballer to play in all four divisions of the English Football League
• Fastest time to lay 12m²of carpet
• Largest scotch egg
• Fastest journey from Land's End to John-O'-Groats on foot (female)
• Most hop the fence yo-yo tricks in one minute
• Largest parade of Mitsubishi cars
• Largest dance class (multi-venue)
• Largest margin of victory by runs in a One-Day International (male)