Castro was cremated on Saturday and his ashes will be carried in a cortege to a final resting place in Santiago de Cuba, the city in eastern Cuba where he launched the revolution.
The government has invited people to Revolution Square for a two-day ceremony starting at 9 am EST. The urn holding the late leader's ashes could be displayed.
Workers rushed to install speakers and light standards in the plaza, where a giant photograph of Castro was draped over the national library, occupying the same space where an enormous poster of Jesus Christ was hung for last year's visit by Pope Francis.
"Who is not going to be affected by a man who did everything for us?" said Jose Luis Herrera, part of the 12-person crew to hang the giant image. "He is the one who guided me and my children. He is my god."
If previous public memorials are any guide, Raul Castro and other government, Communist Party and military leaders will lay flowers near the monument to Cuban national hero Jose Marti, followed by a long line of ordinary Cubans.
The ceremony in the capital will end on Tuesday night when foreign leaders are expected to pay their respects to a man who dedicated his life to fighting capitalist and colonial oppression, aligned his country with the Soviet Union and outlasted nine US presidents who had sought to oust or undermine him.
BIRTHPLACE OF THE REVOLUTION
A cortege will then carry Castro's remains east across the 1,200km long, eyebrow-shaped island to Santiago de Cuba. Nine days of national mourning will come to an end when his cremated ashes are laid to rest in the birthplace of the revolution on December 4.
Along the way, admirers will mourn a man that many here saw as a visionary who stood up to US domination of Latin America, brought healthcare and education to the poor, and inspired socialist movements across the world.
But critics, including exiles concentrated largely in Miami, have celebrated Castro's death, saying he was a tyrant who jailed his opponents, banned opposition parties and wrecked Cuba's economy with a failed socialist experiment.
Reacting to his death, US elected President Donald Trump called Castro "a brutal dictator who oppressed his own people for nearly six decades".
Trump has also has threatened to reverse outgoing President Barack Obama's rapprochement with Cuba, which included restoring diplomatic relations and easing a half-century economic embargo.
Tourists passed through Revolution Square on Sunday, snapping photos and taking joy rides in classic US cars from the 1950s that are still widely used.
"What I have been impressed with is the love that the Cuban people had for him," said Martha Pons, a Mexican tourist who came to Cuba to attend a Placido Domingo concert on Saturday that was postponed after Castro's death.
Cuba's rich variety of music, a soundtrack on the streets of Havana, has been muted since Friday night and the government has also temporarily banned alcohol sales and suspended the professional baseball season.