Builder Caspar Wever and designer James Lloyd completed the viaduct for the Baltimore and Ohio Railroad in November 1829, at an officially listed cost of $58,106.73 -- though the actual price may have climbed as high as $100,000. The bridge stretches 312 feet across Gwynns Falls near Carroll Park, built from heavy granite blocks quarried at Ellicott's Mills and Port Deposit. A full-centered arch spans the creek, and the deck carries space for two railroad tracks. During construction, a temporary wooden framework supported 1,500 tons of stone for the central span. An arched passageway was built through one of the masonry approaches to provide an underpass for a wagon road. The original design called for a single arch with a shorter chord, but the proprietor of mills upstream feared a narrower opening would cause flooding, so the dimensions were enlarged. A white cornerstone at one end bears the inscription: "James Lloyd of Maryland, Builder A.D. 1829."

The Carrollton Viaduct occupies a peculiar place in American transportation history: it is both a monument to the railroad age and a relic of the era before it fully arrived. When Andrew Jackson crossed the bridge on June 6, 1833, traveling between Ellicott's Mills and Baltimore, he became the first sitting President of the United States to ride a railroad train. The bridge beneath his car was barely four years old. The B&O Railroad itself had been founded only in 1827, and the Carrollton Viaduct was among its earliest infrastructure investments -- a bet in stone that railroads would endure. That bet has paid off for nearly two centuries. The bridge has provided continuous service to the Baltimore and Ohio Railroad and its modern corporate successor, CSX Transportation, carrying loads far greater than anything Wever or Lloyd envisioned.

Recognition came slowly but emphatically. On November 11, 1971, the Carrollton Viaduct was designated a National Historic Landmark and simultaneously listed on the National Register of Historic Places. In 1982, the American Society of Civil Engineers designated it a National Historic Civil Engineering Landmark, placing it alongside works like the Brooklyn Bridge and the Panama Canal in the pantheon of American engineering achievements. The viaduct remains one of the oldest railroad bridges in the world still carrying rail traffic. Its longevity is a testament to the quality of its construction -- the granite arches and walls have weathered nearly two hundred years of freight loads, weather, and the vibration of countless trains. Today, CSX Transportation owns and operates the bridge, and its trains rumble across Gwynns Falls along the same route that carried Andrew Jackson into a new era of travel.