The United Nations was born during the middle of World War II as the world seemed to be coming apart. Though its founding is officially celebrated in October, it was 72 years ago on Monday that 50 of the original member states signed the Charter of the United Nations after unanimously passing it the day before.

Since its founding, the organization has faced its share of criticism. Its agencies are credited with boosting health and education levels and helping to save millions of lives. But it has often been accused of being bloated and undemocratic, with just a few member states calling most of the shots.

President Franklin D. Roosevelt pushed for the creation of the U.N. during the deadliest war in human history as the key to preventing another massive global conflict. It was Dag Hammarskjöld, the second U.N. secretary general, who said the entity “was created not to lead mankind to heaven but to save humanity from hell.”

The U.N. Charter gave the organization the authority to maintain international security, establish democracies and promote peace. Here’s a look at five of its biggest aid agencies.