The town that Mario, Luigi, Yoshi, E Gadd, Peach, and some others live in.
Toad town is recurrent location in the Mario Series. The layout of the town changes just like Peach's Castle in each game. It is depicted as cheery and flourishing place.
According to Paper Mario Series, it has a massive sewer system that can take you anywhere in the kingdom. This could be just part of the Pipe Maze for it also take you anywhere in the kingdom. The only difference is the sewer pipes are blue instead of green.