US President Barack Obama will turn from sightseeing to state business on his historic Cuba trip, pressing President Raul Castro for economic and democratic reforms while hearing complaints about continued US economic sanctions.

Obama and Castro will have their fourth meeting, likely their most substantial, on Monday at the Palace of the Revolution, where Castro and his predecessor, older brother Fidel Castro, have led Cuba’s resistance to US pressure going back decades.

A US presidential visit to the inner sanctum of Cuban power would have been unthinkable before Obama and Raul Castro’s rapprochement 15 months ago, when they agreed to end a Cold War-era dispute that lasted five decades and continued even after the collapse of the Soviet Union.

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The two leaders have deep differences to discuss as they attempt to rebuild the bilateral relationship.

Obama is under pressure from critics at home to push Castro’s Communist government to allow dissent from political opponents and further open its Soviet-style command economy.

Members of the Ladies in White group are arrested during their protest in Havana. Photo: ABC

His aides have said Obama will encourage more economic reforms and greater access to the internet for Cubans. His administration hopes such changes might come at a Communist Party congress next month but doubts any political opening will be forthcoming.

Still, Obama has promised to talk about freedom of speech and assembly in Cuba.

Castro has said Cuba will not waver from its 57-year-old revolution and government officials say the US needs to end its economic embargo and return the Guantanamo Bay naval base to Cuba before the two nations can enjoy normal relations.

Besides meeting Castro, he also plans to visit a state-owned micro brewery and attend a state dinner on Monday.

On Tuesday, he will deliver a speech on live Cuban television and attend an exhibition game between Major League Baseball’s Tampa Bay Rays and Cuba’s national team.

Obama has ended his first day in Cuba with a walk and a family dinner in Old Havana, where he received a warm welcome from Cubans who were eager to see him despite the heavy rain that fell in the capital city.

¿Que bolá Cuba? Just touched down here, looking forward to meeting and hearing directly from the Cuban people.

— President Obama (@POTUS) March 20, 2016

Many Havanans gathered on Sunday in the streets near the route through the historic quarter of the city to welcome the first US president to visit the island in nearly 90 years.

The tour of Old Havana, which Obama had planned to make with his wife Michelle, his two daughters Malia and Sasha and his mother-in-law Marian Robinson, who accompanied him on this trip, was also modified.

As they walked through the narrow streets of Old Havana and Centro Havana, hundreds of residents took photos from balconies and doors and welcomed them with applause and cheers.

To end the day, the presidential family chose to dine privately at the San Cristobal restaurant situated in Centro Habana.