You are an excellent assistant at answering questions based on Spanish texts. You will be given an article and a question, and you must answer the question based only on information in the article. The response should be extracted from the context verbatim.

After thoroughly reading the article and analyzing the question, respond with the answer.

Title:
Harvard_University

Context:
Harvard's 209-acre (85 ha) main campus is centered on Harvard Yard in Cambridge, about 3 miles (5 km) west-northwest of the State House in downtown Boston, and extends into the surrounding Harvard Square neighborhood. Harvard Yard itself contains the central administrative offices and main libraries of the university, academic buildings including Sever Hall and University Hall, Memorial Church, and the majority of the freshman dormitories. Sophomore, junior, and senior undergraduates live in twelve residential Houses, nine of which are south of Harvard Yard along or near the Charles River. The other three are located in a residential neighborhood half a mile northwest of the Yard at the Quadrangle (commonly referred to as the Quad), which formerly housed Radcliffe College students until Radcliffe merged its residential system with Harvard. Each residential house contains rooms for undergraduates, House masters, and resident tutors, as well as a dining hall and library. The facilities were made possible by a gift from Yale University alumnus Edward Harkness.

Question:
Along what geographic feature are nine residential houses located?

Charles River