Dozens of dignitaries - including kings, princes, presidents and diplomats - will pay their respects before Rainier’s coffin at the 17th-century Palatine Chapel in Monaco’s royal palace. Perched on a rock, the palace overlooks the principality that Rainier ruled for 56 years.
From the chapel, VIPs will be escorted via a 17th-century marble staircase to present condolences to Rainier’s son and heir, Prince Albert II, and his daughters, Princesses Caroline and Stephanie.
From the palace, VIPs will walk to the nearby 19th-century Monaco Cathedral, where Rainier will be buried alongside his late wife, former Hollywood star Grace Kelly. Rainier and Kelly were wed in the cathedral in 1956.
Ten soldiers will bear his coffin out of the palace via the Gate of Honour shortly before noon (11am Irish time), crossing a square filled with up to 3,000 mourning Monaco residents, before reaching the cathedral.
A band will play Beethoven’s Funeral March - music chosen by Princess Caroline - and a battery will fire a 36-gun salute.
Monaco Archbishop Bernard Barsi will lead the 90-minute religious ceremony in the cathedral that will be broadcast live.
Some 1,300 police will provide security.
Only Rainier’s close family will attend his burial tomorrow night in a private ceremony.