Follow CBSMIAMI.COM: Facebook | Twitter

MIAMI(CBSMiami) — Security was tight and the mood festive in the Colombian city of Cartagena on Monday as leftist guerrillas and the government prepared to sign a historic peace agreement.

United Nations Secretary-General Ban Ki-Moon flew in to join leaders from around the region and the world, and of international organizations, to witness the signing ceremony in the coastal city later the same day.

The more than 2,500 guests have been invited to wear white as a sign of peace, and Colombian President Juan Manuel Santos will put his signature on the 297-page accord with a pen made from a recycled shell used in combat.

A nationwide referendum on the accord will take place on October 2nd.