Important International Boundary Lines
| Name of Boundary Line | In Between Countries |
| Durand Line | The Durand Line was a frontier boundary between Afghanistan and British India. It was established after an 1897 memorandum of understanding (MoU) between Mortimer Durand of British India and Afghan Amir Abdur Rahman Khan. |
| Radcliffe Line | On 17th August 1947 the Radcliffe Line was declared as the boundary between India and Pakistan. |
| MacMahon Line | Between India and China. |
| Hindenburg Line | Between Germany and Poland, built in 1916–1917 during First World War. Built by Germans. |
| Maginot Line | Between France and Germany. French built after the First World War. |
| Oder Neisse Line | International border between Germany and Poland. |
| Siegfried Line | The Siegfried Line was the German defensive line and on the opposite Maginot Line. |
| 17th Parallel Line | North Vietnam and South Vietnam |
| 38th Parallel Line | North and South Korea |
| 49th Parallel Line | USA and Canada |
