Hatfield House is a grand Jacobean country house set in Hatfield, Hertfordshire, England, about 20 miles north of London.  It is still the home of the Cecil family (the Marquesses of Salisbury) and is open to the public as a historic house and tourist attraction.
 
Hatfield House was completed in 1611 for Robert Cecil, 1st Earl of Salisbury and chief minister to King James I, making it a classic example of a “prodigy house” from the Jacobean era.  The estate sits in a large park known as the Great Park, with formal gardens extending across about 40 acres.
 
The house stands on the site of the earlier Old Royal Palace of Hatfield, where Queen Elizabeth I spent much of her youth and in 1558 was told she had become queen.  Part of that Tudor palace (the Great or Banqueting Hall and some brickwork) survives within the grounds and is still used for events.
 
The grounds include the Queen Elizabeth Oak (linked to the legend of her accession) and later‑formed formal gardens such as the knot garden and private Celadon Garden.
 
Interesting facts...
Tradition says that in November 1558 the young Elizabeth Tudor was sitting under this great oak when she was told that her half‑sister Mary I had died and that she herself was now queen of England. Although the current oak was planted in 1985 by Queen Elizabeth II.