Horse Guards Parade
From the Super Mario Wiki, the Mario encyclopedia
Horse Guards Parade is an open area in London that appears as a location in both versions of Mario & Sonic at the London 2012 Olympic Games. It appears as the venue for the Beach Volleyball Event in the Wii version, and while not explicitly stated in the game, it serves as the Nintendo 3DS version's Beach Volleyball venue as well.
In the Nintendo 3DS version's story mode, Horse Guards Parade appears as the location for the episode Corner the Koopa King!, in which Sonic arrives and is attacked by Bowser, followed by Knuckles and Vector arriving to challenge Bowser. After Bowser is defeated, Knuckles breaks the Fog machine, clearing the green Phantasmal Fog from the area, and he stays behind with Vector to interrogate Bowser while Sonic heads back to the Main Stadium. Horse Guards Parade also makes two further smaller appearances in the Story Mode, the first in Clear Skies Again, in which it is revealed that Bowser was a 3D hologram when Knuckls tries to punch him, and once again in The Grand Showdown, in which Donkey Kong, Knuckles and Vector call Mario, Luigi, Sonic and Tails to tell them that they had cleared the area of the fog.