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Reality Checkpoint is the name given to a large lamp-post in the middle of Parker's Piece, located at the intersection of the park's diagonal paths. The name comes from an unofficial inscription which has been painted on the lamp-post since the early 1970s. The lamp-post is also believed to be the oldest electrical lamp-post in Cambridge.
There are four main theories as to the meaning of the name.
1.It may mark the boundary between the central university area of Cambridge (referred to as the 'reality bubble') and the 'real world' of non-academic locals living beyond. One is warned to check one's notions of reality before passing. For students at Cambridge, who walk out to Mill Road across Parker's piece for an evening in the 'real world', usually including a visit to one of Mill Road's selection of pubs, the lamp-post marks the end of the 'reality holiday' as they walk back to central Cambridge - back into 'the bubble'.
2.The name arose because the lamp-post forms a useful landmark for people crossing the park at night—perhaps inebriated or in the fog—since it is the only light for hundreds of yards.
3.When drunk, students and the general public are reminded to check they are able to walk like a sober person before passing the police station just a few hundred metres away.
4.The post being situated in the middle of two walking paths that intersect, anyone walking whilst not tuned in to "reality" will probably collide with the lamp-post, hence "reality checkpoint".

Parker's Piece is a 25-acre flat and roughly square green common located near the centre of Cambridge and is now regarded as the birthplace of the rules of Association Football. The two main walking and cycling paths across it run diagonally, and the single lamp-post at the junction is colloquially known as Reality Checkpoint TL4558 : Reality Checkpoint, Parker's Piece. The area is bounded by Park Terrace, Parkside, Gonville Place, and Regent Terrace. The Cambridge University Football Club Laws were first used on Parker's Piece and adopted by the Football Association in 1863.
The grass is well manicured and it is known today chiefly as a spot for picnics and games of football and cricket, and serves as the games field for nearby Parkside Community College.
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