Sentence:  In a railway <WSD>control tower</WSD> at Dunkirk, Ohio, Operator Cliff Schwartzkopf waited for the Pennsylvania's Pennsylvanian, eastbound from Chicago to New York. 
Meaning of the word marked with <WSD> tags:  An enclosed, raised structure occupied by one or more persons who operate or exercise control over railway traffic, ship movement, a racetrack, machinery, etc.