Byline: Joe Riley
But also a date not without its own inbuilt irony, as Prince Charles gave the Royal seal of approval to an idea that began on the back of an envelope.
Charles's great-great-great grandfather, Prince Albert, would have been, like his wife Queen Victoria, more than amused.
For he opened the original Albert Dock in 1846.
The site may once have been described as "a hideous pile of naked brickwork", but here it was again - risen phoenix-like from decay and transformed into a thing of beauty, its pale mellow pink facades re-lit by morning and evening sunlight.
Next month, it's not only the Tate, but the whole of the Dock complex, which celebrates the 20th anniversary of that transformation.
The dock site - Europe's largest mass of Grade I-listed buildings - was partly erected by French prisoners of war under the guidance of titanic engineer "Big" Jesse Hartley.
It epitomised Liverpool's maritime history. But it was also a time to dispel urban myths.
Michael Heseltine, who, as the post-Toxteth Riots Minister for Merseyside, came to Liverpool once every 10 days for 18 months, put paid to the idea that the waterfront revolution was a direct result of the disturbances.
He told me at the time: "Some people mistakenly believe that.
"It all started two years before that.
"I put the idea for restoring the area on the back of an envelope to give to my permanent secretary on the day I joined the Cabinet in 1969.
"It was a part of things I wanted to get on with at the Department of the Environment."
Heseltine joined Prince Charles virtually incognito - and was lying in wait just next to one of the opening-day prize exhibits, a 1936 Salvador Dali of a telephone with a handset in the form of a lobster.
Quite what everyone made of the art was something else.
Some of it clearly confused Margaret Thatcher's new inner-city specialist, David Trippier.
Merseyside's chief constable, Sir Ken Oxford, was spotted gently prodding the famous (or was it infamous?) sculpture of sliced bread with his silver-topped ceremonial walking stick.
"Yes, it is covered in wax," he announced on completing his investigations.
Others, who could not see the wood for the trees - even when some of the trees were made of cardboard - had a lovely time celebrity spotting. Like film-maker David Puttnam, seen chatting to cricketer Clive Lloyd. And there was the Hon Angus Ogilvie, the Duke of Westminster, the Hon Simon Sainsbury, Sir Mark and Lady Weinberg, Sir John Moores, Alex Bernstein, Sir Anthony and Lady Caro, the Countess of Airlie, Antony Pilkington and David Plowright.
The list was as long as it took for Prince Charles to emerge from the Tate into the afternoon sunshine to mingle with Joe Public.
And that took two hours.
That's when Samantha Snape, a 20-year-old hairdresser from Ainsdale, presented Charles with a Lancastrian red rose.
The Prince, already sporting a red carnation in his buttonhole, responded: "I should really be presenting it to you."
For the record, the Prince declared the Albert Dock open at 10. …