Please answer the following question: Question: "What is the center of the colleges?"  Context: "While Harkness' original colleges were Georgian Revival or Collegiate Gothic in style, two colleges constructed in the 1960s, Morse and Ezra Stiles Colleges, have modernist designs. All twelve college quadrangles are organized around a courtyard, and each has a dining hall, courtyard, library, common room, and a range of student facilities. The twelve colleges are named for important alumni or significant places in university history. In 2017, the university expects to open two new colleges near Science Hill."  Answer:
Answer:
a courtyard