The Great Eastern Main Line is the railway line from London Liverpool Street to Ipswich and Norwich. The route also diverges in several places to serve Harwich, Clacton and Southend.

The main towns served by the route, starting from London, are listed below. Towns in bold are served by fast InterCity services.

• London Liverpool Street
• Stratford
• Ilford
• Romford
  • Branch line diverges to Upminster
• Shenfield
  • Line diverges to serve Billericay and Wickford, where the line diverges to serve either Southend-on-Sea or Southminster
• Chelmsford
• Witham
  • Branch line diverges to Braintree
• Marks Tey
  • Sudbury Branch Line diverges to Sudbury
• Colchester
  • Line diverges to serve Walton-on-the-Naze and Clacton-on-Sea
• Manningtree
  • Line diverges to serve Harwich
• Ipswich
  • Line diverges to serve Felixstowe branch line, or the East Suffolk Line to Lowestoft (which includes the branch line to Leiston for Sizewell nuclear power station.)
• Stowmarket
  • Line diverges to serve Bury St. Edmunds then Newmarket and Cambridge, or Ely, March and Peterborough
• Diss
• Norwich
  • Line diverges to serve either Lowestoft or Great Yarmouth (via the Wherry Line), or Wroxham, Cromer and Sheringham (via the Bittern Line), or Wymondham, Thetford and Ely.

Passenger services on the route were previously operated by First Great Eastern for commuter services south of Ipswich, and Anglia Railways for fast InterCity services beyond Ipswich. On 1st April 2004, these franchises were merged to form the new 'One' Railway franchise. Since January 2005, the line now uses 110 mph, streamlined Class 90 electrics, unlike before when it used 40 year old Class 86 electric, which had a top speed of 100 mph