Kingdom of Youth

Youth Land is a land in the Super Mario Bros. Super Show! Youth Land appears in only one episode, "Two Plumbers and a Baby / Lost Dog" and is full of giant blocks (that kids play with) and other things babies like. The center of this land has the Pool of Youth a machine that makes anyone, any age. Mario, Luigi, Princess Toadstool and Toad came here, only to be attacked by King Goo Goo Gaga Koopa and get the princess turned into a baby.

Baby Park from Mario Kart: Double Dash!! and Mario Kart DS seems to take place here, even thought it looks more like it takes place on Yoshi's Island.