The Royal County of Berkshire, more commonly known as simply Berkshire (ˈbɑːrkʃɪər,_-ʃər ; abbreviated Berks.), is a ceremonial county in South East England. It is bordered by Oxfordshire to the north, Buckinghamshire to the northeast, Greater London to the east, Surrey to the southeast, Hampshire to the south, and Wiltshire to the west. The county town is Reading.
The county has an area of and a population of 911,403. The latter is concentrated in the east, the area closest to Greater London, and includes the county's largest towns: Reading (174,224) Slough (164,793), Bracknell (113,205), and Maidenhead (70,374). The west is rural, and its largest town is Newbury (33,841). Berkshire is governed by six unitary authorities: Bracknell Forest, Reading, Slough, West Berkshire, Windsor and Maidenhead, and Wokingham. The historic county included the parts of Oxfordshire south of the River Thames, which formed its northern border, but excludes Caversham and Slough.
The Berkshire Downs, a chalk downland and area of outstanding natural beauty, occupy the west of the county. They are the source of the River Kennet, which flows east through Newbury before meeting the Thames at Reading. The Thames then forms Berkshire's northern border, flowing past Maidenhead, before entering the county and flowing past Slough and Windsor. The south-east of the county contains Swinley Forest, a remnant of Windsor Forest now used as a forestry plantation.
There is evidence of prehistoric settlement on the Berkshire Downs, including the Iron Age Uffington White Horse, now in Oxfordshire. In the Anglo-Saxon period the region was contested by Mercia and Wessex, and Alfred the Great was born in Wantage, also now in Oxfordshire. Windsor Castle, which would become the official country residence of the British monarch, was built after the Norman Conquest. The county has been the site of several battles, particularly during the First English Civil War, when Reading and Wallingford were besieged and Newbury was the site of two battles, in 1643 and 1644.