Benjamin Henry Latrobe, II (December 19, 1806 – October 19, 1878) was an American civil engineer, best known for his railway bridges.
He was the son of Benjamin Latrobe, architect of the United States Capitol and the Basilica of the Assumption. The junior Latrobe was born in Philadelphia, Pennsylvania, and was educated in Baltimore, Maryland, and later at Georgetown College. He married Maria Eleanor "Ellen" Hazlehurst on March 12, 1833.
Around 1820 Latrobe worked with his father to establish a water supply for New Orleans, Louisiana. Between 1833 and 1835, as assistant engineer for the Baltimore and Ohio Railroad, he saw his design for the Thomas Viaduct take shape. The viaduct spans the Patapsco River between Relay and Elkridge, Maryland.
Early on it was nicknamed "Latrobe's Folly" as many doubted the massive structure could support itself. The fact that it remains in use as of 2010, carrying far heavier loads than ever envisioned, is a testament to his skill. He later became chief engineer of the Baltimore and Ohio Railroad.