Headquarters of the United Nations However, the UN did reject an unusual "model playground" proposal for that site, instead choosing to construct a play area similar to others found around New York City. The first 450 UN employees started working at the Secretariat Building on August 22, 1950. The United Nations officially moved into the Secretariat Building on January 8, 1951, by which time 3,300 employees occupied the building. At the time, much of the Secretariat Building was still unfinished, and the bulk of the UN's operations still remained at Lake Success. A centralized phone-communications system, was built to facilitate communications within the complex. The
Headquarters of the United Nations as well as a deck over FDR Drive on the headquarters' eastern side. To fit in with the accelerated schedule of construction, the steel would have to be delivered by September. The project also included a four-lane, $2.28 million vehicular tunnel under First Avenue so that traffic could bypass the headquarters when the UN was in session. The tunnel started construction on August 1, 1949. The tunnel involved two years of planning due to its complexity. Property inside Tudor City, just west of the headquarters, was also acquired so that two streets near the UN headquarters could be widened. The