It was built not for parliamentary business, but for feasts and banquets.
Long as four cricket pitches and all of it sitting beneath a sublime, soaring oaken roof, it is safe ground for the great British ceremonies that involve parliamentarians and the sovereign.
The latest King Charles came to the hall with his Queen Consort, Camilla, to hear addresses of condolence on the death of his mother, Queen Elizabeth II, from the robed and ruffled and gold-braided Speakers of both the Houses of Commons and the Lords.
His response was his first speech as King to those who run the country, and he took care to assure the massed parliamentarians that though he was sovereign, he had the greatest regard for their roles.
Indeed, that weight of history he felt in the immense hall, he said, “reminds us of the vital parliamentary traditions to which members of both Houses dedicate yourselves with such personal commitment to the betterment of us all”.
Parliament was “the living and breathing instrument of our democracy”. It was also a reminder of the “medieval predecessors of the office to which I’ve been called”.
He offered loving tribute to his late mother, who from Wednesday this week will lie-in-state in Westminster Hall, giving her ordinary subjects four days to file past her coffin.
Quoting Shakespeare’s Henry VIII in reference to Elizabeth I, Charles said Queen Elizabeth II had been “a pattern to all princes living”.
He spoke of the monuments around parliament to her jubilees, singling out the great stained glass window from her diamond jubilee in 2012 that flooded Westminster Hall and all within it with soft light.
And he delivered the promise those in the hall had come to hear: to devote himself to the people of the United Kingdom, just as his mother had done when she became Queen 70 years ago.
“While very young, her late majesty pledged herself to serve her country and her people and to maintain the precious principles of constitutional government which lie at the heart of our nation,” the King said.
“This vow she kept with unsurpassed devotion. She set an example of selfless duty which, with God’s help and your counsel, I am resolved faithfully to follow.”
And with duty done to the sometimes restive parliamentarians – the latest prime minister to be dumped, Boris Johnson, was in attendance, as was the newest, Liz Truss – King Charles III and his Queen Consort were swept safely away in a venerable black Rolls Royce.
Soon, King Charles III was flying to Edinburgh where his late mother’s coffin lay on its final journey from Balmoral Castle in the Scottish Highlands to Westminster Hall and eventually, to a crypt in Windsor Castle.