Three Sisters (Australia)
From Tardis Wiki, the free Doctor Who reference
Three Sisters was a location close to Sydney, Australia, a rock formation found in the Blue Mountains of New South Wales, that Roz Forrester and Chris Cwej visited in 1996. (PROSE: Return of the Living Dad)
Behind the scenes
Dad just mentions the place in passing, without really defining what it is, or giving more than a hint of its real world location in the Blue Mountains.