MASS MoCA, the nation’s largest contemporary art space, is getting even bigger. On Sunday, Nov. 16, the museum known for its art experiments will unwrap an extraordinary art experience — one mile of wall space covered with 100 geometric drawings by the late Sol LeWitt, a founder of conceptual and minimalist art. Sol LeWitt: A Wall Drawing Retrospective is housed in Building No. 7, a 27,000-square-foot space that was renovated especially for the exhibit and is opening to the public for the first time. The LeWitt installation, which will inhabit Building No. 7 for 25 years, expands the MASS MoCA galleries by 25 percent.