The "Daily Shelter" by artist Ingrid Brandth is a dining-room table that converts to a secret fort: "At first glance it looks like an ordinary table. But for the one who knows its secret, it can be transformed into a shelter where one can hide from scary sounds, ghosts or family members. Just like a snail feels safe in its house."
One of the coolest parts of having a two-year-old around the house is getting to play fort all the time -- we dive under the covers and shout "cave of wonders," hide in closets, and so on. I wish I had the chops and the space to build one of these for Poesy, but we're doing OK with blankets and pillows.