Sentence:  His life-long friend , Serge Koussevitzky , gave unreservedly of his praise and brilliant performances in Boston , New York , and <WSD>Washington</WSD> , D. C. , to which he added broadcastings and recordings for the whole nation . 
Meaning of the word marked with <WSD> tags:  the capital of the United States in the District of Columbia and a tourist mecca; George Washington commissioned Charles L'Enfant to lay out the city in 1791