The mattress sits directly on the floor. There is no platform/bed in a box. It’s a floor bed. The screws are quite short, which results in the tent beams being shaky. If you suspect your child may swing from the beam, I would not recommend. We moved the bed from the middle of the room to the corner of the room, and during that time the screws became so loose they all had to be re tightened. The mattress height should be no more than 7” inches if you want it to fit down inside the box. My child is 44” tall. When standing on our 8” inch mattress, the top beam was at his chest. Very tempting for swinging, which is terrifying considering the stability issues. Triple check the return policy before purchase. Recommend (possibly) for a toddler bed, definitely not for preschoolers and up.