187th Street crosses Washington Heights and running from Laurel Hill Terrace in the east to Chittenden Avenue in the west near the George Washington Bridge and Hudson River. The street is interrupted by a long set of stairs east of Fort Washington Avenue leading to the Broadway valley. West of there, it is mostly lined with store fronts and serves as a main shopping district for the Hudson Heights neighborhood.

Answer this question, if possible (if impossible, reply "unanswerable"): What is 187th Street interrupted by?
stairs