His mother gave him his first schooling, and when he was eight he was placed with his elder brother, John H. B. Latrobe, in Georgetown College. In 1817 the father took the family to Baltimore, and soon after that to New Orleans, where in 1820 he died. Returning with his mother to Baltimore, Latrobe attended St. Mary's College as a day student, 1821-1823, taking high honors in mathematics.
Latrobe then read law and practised a short time with his brother before going to Allowaystown, New Jersey, to act as agent for a parcel of land owned there by his mother and his uncle. Soon forced by ill health to leave Allowaystown, he returned to Baltimore, making his home with his brother and again associating with him in practice.
The profession was not to his taste, however, and in 1831, through the influence of his brother, he obtained a position in the engineer corps of the Baltimore & Ohio Railroad. Advancement was rapid on the new road for men with mathematical training and Benjamin Latrobe was soon principal assistant to Jonathan Knight, the chief engineer. In 1832 he was in charge of the survey that located the line from Baltimore to Washington and he later designed and built the outstanding bit of construction of that branch, the Thomas Viaduct at Relay House, nine miles southwest of Baltimore. This stone-arch bridge, named for the first president of the road, was long known as "Latrobe's Folly. "
In 1835 Latrobe left the Baltimore & Ohio to become chief engineer of the Baltimore & Port Deposit Railroad, for which he built the thirty-four difficult miles of road from Baltimore to Havre de Grace, Maryland. The ferries that he employed at Havre de Grace were probably the first of the present type of railroad ferries. Returning then to the Baltimore & Ohio, he directed the survey of the line from Point of Rocks to Harpers Ferry, and as engineer of location and construction (1836), built the road through the mountains from Harpers Ferry to Cumberland.
Upon the completion of this part of the road, Knight resigned as chief engineer, September 30, 1842, and Latrobe was appointed to his position. In 1847 the extension to Wheeling, Va. (W. Va. ), on the Ohio River was authorized, and Latrobe with three corps of engineers started in July of that year to lay out the line, completing the survey to the Ohio the next year. The construction of this road was probably his major work. With 5, 000 men and 1, 250 horses, drilling and loading by hand, blasting with black powder, and hauling with horses, he built 200 miles of road, including 113 bridges and eleven tunnels (one of the longest in the country at the time), in less than four years. The masonry wall construction which still carries the road along the slopes of the hills in the Cheat River Valley and the Kingswood Tunnel (4, 100 feet) were the dramatic features of the task. To permit the opening of the line before the completion of the tunnel a temporary line two miles long with a grade of 10 per cent. (528 feet rise in a mile) was built and operated for passenger service for six months (T. C. Clarke, "The Building of a Railway, " Scribner's Magazine, June 1888).
Latrobe next built the Northwestern Virginia Railroad (1851 - 52) for the Baltimore & Ohio Railroad Company, and in 1871, as chief engineer of the Pittsburgh & Connellsville Railroad, he drove the gold spike that completed this road and the Baltimore & Ohio to Pittsburgh. He originated the railroad unit of work, the "ton mile" (Baltimore & Ohio Annual Report, 1847), and was the authority for the maximum permissible grade of 116 feet to the mile, prescribed in the charters of the transcontinental railroads; he indorsed the proposal of the Magnetic Telegraph Company to lay the first line of the Morse telegraph along the Washington Branch of the Baltimore & Ohio; and he was a member of the committee to which Roebling submitted the plans of the Brooklyn Bridge.
He retired from the railroad in 1875, and died at Baltimore three years later, after a short illness.
On March 12, 1833, at Salem, New Jersey, Latrobe married a cousin, Maria Eleanor Hazlehurst. They were the parents of five children, one of whom, Charles Hazlehurst Latrobe, attained distinction in his father's profession.