Magic Tree House
The Magic Tree House transports its inhabitants to any setting- as long as it's in a book. Want to go to Hogwarts? Read Harry Potter in the Magic Tree House and find yourself on the Quidditch pitch. In The Magic Tree House series, the protagonists, Jack and Annie, visit numerous points in space and time, including Camelot, the Moon several hundred years in the future, and Vesuvius on Volcano Day. The Magic Tree House is similar to the TARDIS in that both can carry a fairly large number of occupants and neither is noticed by passerby in whatever time and place it winds up in. However, it does not have the "bigger on the inside" technology that the TARDIS has, and it is limited to visiting settings in books (whereas the TARDIS is able to go wherever, whenever). It also requires one to climb up to the tree house, which could be difficult when one has been injured or has little time to make a getaway. Due to limitations and possible difficulty entering, the Magic Tree House is a mix of both good and bad design, making it an average time travelling device.