Riddle Time: Ace These Mind-Bending Brain Teasers! I have cities but no houses, forests but no trees, and rivers but no water. What am I? A map A book A dream A puzzle None What has keys but can't open locks? A zookeeper A piano A keyring A lockpick None What has a heart that doesn't beat? A clock A robot A painting A stone None I am taken from a mine and shut in a wooden case, from which I am never released, and yet I am used by almost every person. What am I? Pencil Diamond Air Coal None The more you take, the more you leave behind. What am I? Footsteps Memories Time Words None Time's up Most Popular Most Popular