Bitesize: The clock - A long history...

Historical records of first man-made clocks are dated to the 3500 BC when Ancient Egyptian builders started erecting tall obelisks near their temples and royal residences.
These tall stone structures served the purpose of casting a sun shadow on the precisely decorated spirals that were set on the ground (often infused into walkways) where people could easy see the position of the shadow and the current time of the day.
Even though initial sundial models were created in Babylon, Egyptian scientists took that invention and advanced its use and precision over the period of over 3 thousand years, during which they discovered winter solstice, summer solstice, separation of daytime into “hours” and much more.