Topics of discussion included the cultivation of traditional crops like quinoa, historical disputes such as Argentina's claim to the British-controlled Falkland Islands and initiatives like promoting literacy in the region.
Cuban Foreign Minister Bruno Rodriguez says he was "deeply pleased" and the talks were characterised by an "extraordinary and permanent spirit of solution."
Heads of state are to meet today and tomorrow at the second summit of the Community of Latin American and Caribbean States, or CELAC for its initials in Spanish.
Insulza's chief of staff, Hugo Zela, said the OAS has no record of a secretary-general visiting Cuba.
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The OAS was formed in 1948. In 2009 it ended Cuba's suspension, but Havana said it was not interested in rejoining a group it accuses of obeying Washington's interests.
"The celebration of this summit ... In Havana demonstrates Cuba's importance in the process of Latin American and Caribbean integration," Brazilian President Dilma Rousseff said yesterday. "Only with Cuba will our region be complete."
The United Nations Development Program and other UN agencies "are working very closely to help the Cuban government and people to preserve this area," Ban said.
He later met with President Raul Castro's daughter, Mariela Castro, the island's most visible advocate for LGBT and women's rights as the head of the National Centre for Sex Education.
Some heads of state arrived early and squeezed other activities into their agenda.
Rousseff and Raul Castro presided over a ceremony launching a new port built with Brazilian financing.
The Argentine presidency released photographs of President Cristina Fernandez's lunchtime encounter the previous day with retired leader Fidel Castro and his longtime companion, Dalia Soto del Valle. Fernandez also published them on her official Twitter account.