GMT

The Prime Meridian is the meridian (line of longitude) at which the longitude is defined to be 0°.

The Prime Meridian and its opposite the 180th meridian (at 180° longitude), which the International Date Line generally follows, form a great circle that divides the Earth into the Eastern and Western Hemispheres.

An international conference in 1884 decided the modern Prime Meridian passes through the Royal Observatory, Greenwich in southeast London, United Kingdom,[1] known as the International Meridian or Greenwich Meridian,

This is the view from the Greenwich Observatory across the Thames.