Mr. Darcy's fictional (but expansive) Pemberley estate is set in the real-life Derbyshire county.  Lizzy inadvertently visits him at his home with her aunt and uncle midway through the novel while trying to sightsee in the area. 

"'About a month,' said Elizabeth; and then, unwilling to let the subject drop, added, 'he is a man of very large property in Derbyshire, I understand.'
'Yes,' replied Wickham; 'his estate there is a noble one. A clear ten thousand per annum. You could not have met with a person more capable of giving you certain information on that head than myself—for I have been connected with his family, in a particular manner, from my infancy.”'