Tower 270 (also known as 270 Broadway, Arthur Levitt State Office Building, 80 Chambers Street, and 86 Chambers Street) is a 28-story mixed use building in Downtown Manhattan that was the headquarters of the Manhattan Project that developed the atomic bomb during World War II.
During World War II it was a federal office building. The most prominent tenant was the North Atlantic Division of the U.S. Army Corps of Engineers, which had offices on the 18th floor. The office was to coordinate all United States military construction on the Northeast as well as all of Europe.
The 370 foot/113 meter tall building was built in 1930 on the site of the former headquarters of Chemical Bank (built in 1907 which in turn had replaced a building built in 1848) by developer Robert E. Dowling at a cost of $2.5 million  and was designed by the E.H. Faile & Company.
It has 350,785 square feet (32,589.0 m2) of floor space on a plot with 50 feet (15 m) facing Broadway and 242 feet (74 m) on Chambers.
The building's location gives its name to the Manhattan Project.
The initial proposed name for the development of the atomic bomb was "Laboratory for the Development of Substitute Materials." Fearing the name would draw undue attention, General Leslie Groves changed it to the "Manhattan Engineer District," which was eventually shortened to the Manhattan Project. The name was based on the Corps practice of naming its districts on the basis of their headquarters.
It became the Arthur Levitt State Office Building providing New York City offices for members of the New York State Assembly and New York State Senate. In 2000 it was sold for $33.6 million in a sealed bid transaction that at the time was the highest-valued property sale ever consummated by the State of New York.
It is owned by RAL Companies of Hempstead, New York, of which Robert A. Levine is the principal owner.
Mark Groblewski of RAL was the only civilian given direct access to 270 Broadway, 86 Chambers Street, and 80 Chambers Street to continue construction on this facility, inside fenced in "Ground Zero", in the aftermath of the September 11 attacks. 400 union employees worked for the full duration of the 9/11 Disaster Clean-up. Mr. Groblewski also assisted as a "civilian volunteer" assisting and directing heavy duty industrial earth moving equipment to climb the 10 story pile of steel and concrete debris. This facilitated removal of materials during the earliest "rescue", and "recovery" plan at "Ground Zero". See NYPD/FEMA Greenwich Street Log Book Page 17 - Permission given by the OEM Commissioner Odermatt for Mr. Groblewski's unobstructed access to all of "Ground Zero".
Floors 15 to 28 were converted to 39 condominium apartments in 2003 ranging in size from 1,998 to 8,117 square feet (754.1 m2). Floors 2 through 7 make up office space and 48 rental apartments are between 8 through 15. The office space has a separate entrance on Chambers Street and is identified as 86 Chambers, there are two residential entrances: one is on Broadway for floors 15 through 28 and the other on Chambers for floors 8 through 15.
- Plan $2,500,000 Building at Broadway and Chambers - New York Times - September 21, 1928
- Emporis Profile - emporis.com - Retrieved November 8, 2007
- Why They Called It the Manhattan Project by William J. Broad - New York Times - October 30, 2007
- State Takes Building - New York Times - March 30, 1946
- Caro, Robert A. The Power Broker. p. 814. ISBN 9780394720241.
- Tower 270 - Cityrealty.com - Retrieved November 8, 2007
- Former state office building re-emerges as mixed-use property. - Real Estate Weekly - February 21, 2001