Had to track it down to be sure. No poster but I had a Doctor Who Calendar I got from a Doctor Who convention in NYC.
It was the inside of my door, which was a small piece of plywood on the entrance at the top of the staircase to the attic in our house.
It was small, like Alice in Wonderland and I had to duck to get in and out of there.
But it was bigger on the inside.
On the wall in the middle of the stairwell on the way up to my attic bedroom was an old Footprints poster I’d won in a contest at Church. Jesus the parallel dimensional being who carried me invisibly. I had a sci-fi brain then and now.