Perched along the East River in midtown Manhattan, the exceptional modern buildings of the United Nations Headquarters house an organization with an equally exceptional mission. Designed in the 1940s by the most renowned international architects of the day, including Wallace K. Harrison of the United States, Le Corbusier of France, and Oscar Niemeyer of Brazil, the UN is both an architectural and a historic landmark. The United Nations at 70 documents in gleaming new photography the restoration of the entire building complex. Complementing the chronicle of the restoration by Carter Wiseman is a fascinating first-person essay by Martti Ahtisaari, which discusses the new and challenging issues facing the UN today.