London Terrace, one of New York’s most iconic apartment complexes, takes up an entire city block in the Chelsea neighborhood. It was completed in the early 1930s and is anchored by a quartet of identical towers at its four corners. The monumental red-brick and limestone complex, a mix of rental and cooperative units with , has a total of about 1,700 apartments ranging from pint-sized efficiency studios to sprawling penthouses and combination units, such as one stylishly updated and generously terraced duplex in the building that stands at the corner of West 23rd Street and 9th Avenue that’s just been listed for $7.5 million.