(don't bite your tongue while you have it in your cheek there)
According to the Guinness world records, the Galap (third picture down) is the largest tortoise in the world:
The biggest Aldabra tortoise I know of is Esmeralda, living on Bird Island in the Seychelles. She's a he, and he is >300kg and reputed to be over 170 years old. There's a video of him here: http://www.youtube.com/watch?v=CJ0b5z4o-Mw