Wonderland is the setting for Lewis Carroll's 1865 children's novel Alice's Adventures in Wonderland.
In the story, Wonderland accessed by an underground passage, and Alice reaches it by travelling down a rabbit hole, possibly on the banks of the Thames between Folly Bridge and Godstow. While the location is apparently somewhere beneath Oxfordshire, Carroll does not specify how far down it is, and he has Alice speculate whether it is near the center of the earth or even at the Antipodes. The land is heavily wooded and also grows mushrooms. There are well-kept gardens and substantial houses, such as those of the Duchess and the White Rabbit. Wonderland has a seacoast, where the Mock Turtle lives.
Source: Wikipedia, "Wonderland (fictional country)", available under the CC-BY-SA License.