Minecraft wiki entry for Secret_door, associated text: The painting door is one of the most well known hidden doors in Minecraft. As such, players are likely to check for secret passages even if they are not trying to invade or thieve. To create the door, start by digging a hole in a wall. Next, replace the removed blocks with ones that can hold a painting but can also be walked through. Some commonly used ones are: Signs, Fence gates, Doors, and Trapdoors. Next, cover the entrance with a painting. To do this, look at the lower left-hand corner block of the area you want covered and place. Note that you may need to crouch place if placing on a door or fence gate. If the painting turns out to be the wrong size, break it and try again. In some cases you may need more than one painting to cover everything up.