Four former presidents including George Bush senior and junior are expected to attend the service at Our Lady of Perpetual Help on Saturday. Meanwhile Barack Obama will deliver the eulogy.
But nothing underlines the legacy of the politician known as the Lion of the Senate like the tributes of ordinary members of the public.
Thousands lined the streets to say their own final farewell to the leader, waving flags and clapping.
At the John F Kennedy Presidential Library and Museum - which Senator Kennedy founded in memory of his brother, the slain president - 20,000 more gathered to view his coffin.
Filing past the closed casket – draped in the stars and stripes flag and attended by an honour guard from each branch of the military – they wiped away tears or simply bowed their heads in sombre reflection.
His final resting place will be Arlington National Cemetery in Virginia – the resting place of American heroes, alongside his two brothers JFK, Robert F. Kennedy and former First Lady Jacqueline Kennedy Onassis.
In Britain he was remembered too, with Gordon Brown praising him for a record of achievements that "surpasses those of many presidents".
He recalled many a summer holidaying in Cape Cod, Massachusetts and discussing politics with the late senator as he skillfully navigated them through the waters on his boat.