NASA's Kennedy Space Center in Florida has two of the largest vehicles ever built on treads. Crawler-transporter No. 1 and crawler-transporter No. 2 (CT-1 and CT-2) have carried rockets and spacecraft to the launch pad for the last 50 years.
Since the Space Shuttle couldn't very well fly itself to the launch pad, NASA had to figure out how to get $1.7 billion worth of spacecraft from the Vehicle Assembly Building the the Launch Pad. Their solution: the 2700-ton Crawler-Transporter. Problem solved.