A bridge is a structure built to span a physical obstacle, such as a body of water, valley, or road, without closing the way underneath. It is constructed for the purpose of providing passage over the obstacle, usually something that can be detrimental to cross otherwise. There is no standard way to measure the total length of a bridge. Some bridges are measured from the beginning of the entrance ramp to the end of the exit ramp. Some are measured from shoreline to shoreline. Yet others use the length of the total construction involved in building the bridge.
Here are the top 20 longest bridges in the world.
| Rank | Bridge | Country | Length |
| 1. | Danyang–Kunshan Grand Bridge | China | 164,800 m (540,700 ft) |
| 2. | Changhua–Kaohsiung Viaduct | Taiwan | 157,317 m (516,132 ft) |
| 3. | Tianjin Grand Bridge | China | 113,700 m (373,000 ft) |
| 4. | Cangde Grand Bridge | China | 115,900 m (380,200 ft) |
| 5. | Weinan Weihe Grand Bridge | China | 79,732 m (261,588 ft) |
| 6. | Bang Na Expressway | Thailand | 54,000 m (177,000 ft) |
| 7. | Beijing Grand Bridge | China | 48,153 m (157,982 ft) |
| 8. | Lake Pontchartrain Causeway | United States | 38,442 m (126,122 ft) |
| 9. | Line 1, Wuhan Metro Bridge | China | 37,788 m (123,976 ft) |
| 10. | Manchac Swamp Bridge | United States | 36,710 m (120,440 ft) |
| 11. | Jakarta-Cikampek Elevated Toll Road | Indonesia | 36,400 m (119,400 ft) |
| 12. | Sheikh Jaber Al-Ahmad Al-Sabah Causeway Main Link | Kuwait | 36,140 m (118,570 ft) |
| 13. | Yangcun Bridge | China | 35,812 m (117,493 ft) |
| 14. | Hangzhou Bay Bridge | China | 35,673 m (117,037 ft) |
| 15. | Runyang Bridge | China | 35,660 m (116,990 ft) |
| 16. | Lima Metro Line 1 | Peru | 33,000 m (108,000 ft) |
| 17. | Donghai Bridge | China | 32,500 m (106,600 ft) |
| 18. | Temburong Bridge | Brunei Darussalam | 30,000 m (98,000 ft) |
| 19. | Shanghai Maglev line | China | 29,908 m (98,123 ft) |
| 20. | Dwarka Sector 8 Metro Station-Rama Krishna Ashram Marg Metro Station | India | 29,808 m (97,795 ft) |
