Doubting Castle

Doubting Castle, a castle belonging to Giant Despair in the “Pilgrim's Progress,” which only one key could open, the key Promise.

Definition taken from The Nuttall Encyclopædia, edited by the Reverend James Wood (1907)

Doubs * Douce, Francis
Dorothea, St.
Dorpat
D'Orsay, Count
Dorset
Dort
Dortmund
Dory, John
Do-the-Boys'-Hall
Douay
Doubs
Doubting Castle
Douce, Francis
Douglas
Douglas-1
Douglas, Gawin
Douglas, Sir Howard
Douglas, John
Douglas, Stephen Arnold
Douglass, Frederick
Doulton, Sir Henry
Douro