Instructions: Answer the question from the given passage. Your answer should be directly extracted from the passage, and it should be a single entity, name, or number, not a sentence.
Input: Passage: The University is organized into eleven separate academic units—ten faculties and the Radcliffe Institute for Advanced Study—with campuses throughout the Boston metropolitan area: its 209-acre (85 ha) main campus is centered on Harvard Yard in Cambridge, approximately 3 miles (5 km) northwest of Boston; the business school and athletics facilities, including Harvard Stadium, are located across the Charles River in the Allston neighborhood of Boston and the medical, dental, and public health schools are in the Longwood Medical Area. Harvard's $37.6 billion financial endowment is the largest of any academic institution. Question: What river is located in the vicinity of the school?
Output:
Charles