There are some things in the Fable series that are unsolved and unknown about. Here is a list of them.
Fairfax secret Modifier
There is a gate in the Fairfax Tomb. When you enter, you are in a room, and at the other end is a gate, with stairs going up. There is currently no known way of opening it. There is also a Flit Switch Obelisk in a room further along the tomb, but with no Flit Switch to activate it. Additionally, the stairs appear to be a dead end, although there may be a right turn or an area which the Hero drops down from (similar to Archon's Knot. They may, however, just be tricks of light and shadow as the area is observable only from a very few angles. Some people believe that there is a reverse for the Potion of Transmogrification on the other side of the gate.
Doors in Bowerstone Modifier
Some houses in Bowerstone Market and Bowerstone Old Town, have a dark door in the back of the room. These doors can't be broken, they don't open up when you buy the house, you can only knock on them, but nothing ever happens. There exists a house in Old Town with one of these said doors which leads to a small space behind it, which is oddly void of anything. The house in question is right next to the potion and weapon stalls (which only appear if Derek was given the warrants during the childhood quests). Furthermore, a house on Fairfax Road (specifically, it's the one directly next to the House of the Ghostly Puffin) in Bowerstone Market also has a door which leads to a small area behind the house. Behind this door is a treasure chest containing a random item or gold, and an outhouse. These doors were most likely placed in nearly every house model in Bowerstone by the designers in order to allow access to what ever might be placed behind the houses.
House in Old Town Modifier
In Bowerstone Old Town, when you enter from Market road, on the right there is a small structure, and next to it, there is a door that has been oddly raised off the ground, making it inaccessible. You can enter it by having a large amount of people following you, and by walking into the space between the door and the small structure. Your followers will try to enter the same space as you and after they are close enough to you, you will get pushed up high enough to enter. Inside is just an empty house that is dark from lack of light. The house has three floors, although you can't access the lowest, and is completely void of furniture. You cannot buy this house and you can only get to it if you chose to give the warrants to the guard during your childhood.