Meridian Utama ya iku meridian (garis bujur) kang bujuré ana ing 0°.

Meridian Utama saka Kutub Lor ngliwati kutha Greenwich, London ing Inggris, Perancis, Spanyol, Aljazair, Mali, Burkina Faso, Togo, lan Ghana, banjur ngliwati Kutub Kidul.

Pranala njaba 
 
 scanned TIFFs of the conference proceedings
 Prime meridians in use in the 1880s, by country 
 Canadian Prime Meridian

Greenwich