Rosbys Rock is a sandstone boulder located along Grave Creek and the former route of the Baltimore & Ohio Railroad in Marshall County southeast of Moundsville, West Virginia. The unincorporated community of Rosbys Rock is so-named for the boulder.
The rock became famous in 1852 after the last spike was driven into the railroad there, completing the line from the the Ohio River at Wheeling, West Virginia, from the Cheapeake Bay at Baltimore, Maryland.
The boulder is approximately 24,300 cubic feet and weighs approximately 1,653 tons.
Interest in the rock has been compounded as a result of a mistake in the inscription chiseled on its face. The craftsmen who memorialized the track closing inscribed an additional "E," spelling the name ROSEBY'S. The mistake was somewhat altered in the painting that overlays the inscription in which the "E" has been altered as a "B," giving the appearance of ROSBBY'S.