Mastercard headquarters, Purchase (formerly IBM Corporate Office Building)

Planning started in October 1977, construction in December 1979, and the building was finished in August 1984. Its lead designers were I. M. Pei and John L. Sullivan III of I. M. Pei & Partners; the landscape is by Hanna/Olin. It was built for IBM.

In January 1995 Mastercard International was planning to move every employee of its New York headquarters there before the year was out. It left Manhattan for a 47-acre (about 19 hectare) property, taken on a twenty-year lease with an option to buy. In 2013 Mastercard began a multi-million-dollar renovation of the headquarters, to house its existing staff and 270 new jobs.

The land, formerly abandoned farmland, is half rural. The client asked for a complex that would express solidity and strength while easing neighbours' worries about the spread of corporate headquarters. The firm therefore broke the office building into three connected parts and tucked a three-level staff garage into a hillside, where it cannot be seen. The whole sits a quarter of a mile (about 400 m) back from the street, half hidden in an out-of-the-way corner of the grounds. It covers less than a fifth of them, leaving some forty acres as open green land.

At the centre, a parallelogram with a saw-toothed outline serves as the building's working and ceremonial heart; two quarter-circle wings join it on the north and west. All three parts are arranged around atria under skylights, which help people find their way, foster a sense of community and let in light and colour. Reflective glass walls running from floor to ceiling draw the outdoors inside. The facades combine travertine and architectural concrete. In 1986 the building received the American Institute of Architects' National Honor Award.

The building houses Mastercard's global headquarters.

The building is in Purchase, Westchester County, near the county airport. It is a working corporate headquarters.