A mobile structure includes first and second rigid frames and first and second horizontal roof supports supported by the rigid frame. Each of the rigid frames includes a first vertical support, a second vertical support substantially parallel to the first vertical support, and a lateral rigid frame support extending perpendicularly at least from the first vertical support to the second vertical support. The mobile structure further includes a floor under the first and second horizontal roof supports, a wheel-axle assembly under the floor, and leveling assemblies that are extendable away from the floor. Each leveling assembly is in weight-bearing and in-line relationship with respect to one of the vertical supports of the first rigid frame.