Conservative, Mr Juan Manuel Santos, took office on Saturday as Colombia's new president, to succeed his former boss Alvaro Uribe with a four-year mandate.
The ceremony in Bogota's Bolivar Square was attended by some 5,000 invited guests, as well as most Latin American and Caribbean leaders including presidents Luiz Inacio Lula da Silva of Brazil, Felipe Calderon of Mexico and Cristina Fernandez de Kirchner of Argentina.
A journalist and economist by training, Santos is a member of one of Colombia's wealthiest and most powerful families. He has vowed to maintain Uribe's hard line against Marxist rebels and to continue his predecessor's business-friendly economic policies.
Uribe was constitutionally barred from seeking another term.