The line of the Prime Meridian defines the eastern and western hemispheres of the globe, first established in 1884 after the International Meridian Conference was held. The line at the Royal Observatory is a physical representation of the imaginary line defined during that time frame. Many were involved in the creation of the Prime Meridian as astronomers, railway engineers, geographers, and more established need for a unified time and location system, conducted studies, took measurements, and made observations. If you visit the Prime Meridian line, you can officially stand with one foot in the East and one foot in the West, making it an appealing tourist attraction and place to take photos. If you want to visit the line, it is included within a purchase to visit the Royal Observatory. The physical line is in the Meridian Courtyard, referred to as "the historic heart of the Observatory, surrounded by the Meridian Observatory – home to the telescopes that helped define zero degrees longitude – and Flamsteed House, the oldest part of the Observatory" ("Stand on the Prime Meridian Line").

"Stand on the Prime Meridian Line." Royal Museums Greenwich, https://www.rmg.co.uk/royal-observatory/attractions/stand-on-prime-merid...