A mighty oak tree once marked the spot we're looking for in Thursday's Geo Quiz.
A five thousand year old dense forest of towering black oak trees once covered this eastern region of England.
Now its mostly farmland and bogs spread out along the Great Ouse River.
Recently a farmer made a discovery there near Cambridgeshire when his plow hit a massive oak tree buried in the wet soil.
Experts have now recovered the perfectly preserved 5,000-year-old timber.
So what's the name this marshland?
The ancient tree was found buried in farmland in the east of England – at the edge of something called the Fens.
The Fens is the answer to our Geo Quiz.
Hamish Low is overseeing the recovery of the black oak from the Fens.