Mexico and the United Nations headquarters in New York City and to the other main UN agencies based in Geneva, Nairobi, Paris, Rome and Vienna. Mexico and the United Nations Mexico is one of the 51 founding members of the United Nations and was admitted into the organization in 1945. Since then, Mexico is a full member of all the UN agencies and participates actively within the organization and has diplomatic relations with most member states. On 26 June 1945, Mexico was represented in San Francisco by Ezequiel Padilla Peñaloza, Francisco Castillo Nájera and Manuel Tello Baurraud in the signing of the United Nations Charter.
Headquarters of the United Nations the complex opened in 1950, were expected to take about 7 years to complete. When completed the complex is also expected to be more energy efficient and have improved security. A temporary $140 million "North Lawn Building" was built to house the United Nations' "critical operations" while renovations proceeded. Work began on May 5, 2008, but the project was delayed for a while. By 2009 the cost of the work had risen from $1.2 billion to $1.6 billion with some estimates saying it would take up to $3 billion. Officials hoped the renovated buildings would achieve a LEED Silver rating.