The Resplendent Manor of Vanderbilt and O'Sullivan, usually known as Vanderbilt-O'Sullivan Manor, The Grand Mansion, or simply The Mansion, is a place that Nathaniel O'Sullivan and Samuel Vanderbilt built and live in. Paxton Vanderbilt also lives there, but is not seen there often, because he mainly sleeps (unless getting ready for a baseball game). Nathaniel and Sam's Webkinz also live there. There is a room in which several Little League uniforms are hung up.
The mansion is painted in powder blue and white, with a giant kaleidoscope dome on top that the inhabitants can go into. When they enter it, it features the sky as if in a kaleidoscope.