Belgium
From Tardis Wiki, the free Doctor Who reference
Belgium is a nation in western Europe.
In 1914, the Doctor and Rose Tyler visited Belgium. (DWAM: Warfreekz!)
In 2001, Anji Kapoor and Dave Young took a holiday in Brussels, Belgium. (EDA: Escape Velocity)
Minor references
The Doctor's psychic paper convinced a Alexandra Tower security guard that he (the Doctor) was the king of Belgium. (DW: The Idiot's Lantern)
Circa 2007 the sale of Dogon eyes had some popularity by collectors of alien artefacts, especially in Belgium for some unknown reason. (TW: Random Shoes)