<P> Windsor Castle was originally built by William the Conqueror in the decade after the Norman conquest of 1066 . William established a defensive ring of motte and bailey castles around London ; each was a day 's march -- about 20 miles ( 32 km ) -- from the city and from the next castle , allowing for easy reinforcements in a crisis . Windsor Castle , one of this ring of fortifications , was strategically important because of its proximity to both the River Thames , a key medieval route into London , and Windsor Forest , a royal hunting preserve previously used by the Saxon kings . The nearby settlement of Clivore , or Clewer , was an old Saxon residence . The initial wooden castle consisted of a keep on the top of a man - made motte , or mound , protected by a small bailey wall , occupying a chalk inlier , or bluff , rising 100 ft ( 30 m ) above the river . A second wooden bailey was constructed to the east of the keep , forming the later Upper Ward . By the end of the century , another bailey had been constructed to the west , creating the basic shape of the modern castle . In design , Windsor most closely resembled Arundel Castle , another powerful early Norman fortification , but the double bailey design was also found at Rockingham and Alnwick Castle . </P>
<P> Windsor Castle was originally built by William the Conqueror in the decade after the Norman conquest of 1066 . William established a defensive ring of motte and bailey castles around London ; each was a day 's march -- about 20 miles ( 32 km ) -- from the city and from the next castle , allowing for easy reinforcements in a crisis . Windsor Castle , one of this ring of fortifications , was strategically important because of its proximity to both the River Thames , a key medieval route into London , and Windsor Forest , a royal hunting preserve previously used by the Saxon kings . The nearby settlement of Clivore , or Clewer , was an old Saxon residence . The initial wooden castle consisted of a keep on the top of a man - made motte , or mound , protected by a small bailey wall , occupying a chalk inlier , or bluff , rising 100 ft ( 30 m ) above the river . A second wooden bailey was constructed to the east of the keep , forming the later Upper Ward . By the end of the century , another bailey had been constructed to the west , creating the basic shape of the modern castle . In design , Windsor most closely resembled Arundel Castle , another powerful early Norman fortification , but the double bailey design was also found at Rockingham and Alnwick Castle . </P>
when was the royal castle in england built
when was the royal castle in england built
in the decade after the Norman conquest of 1066
in the decade after the Norman conquest of 1066