Barbara Amarteifio stared as a woman climbed the spiral staircase of Louise Bourgeois' sculpture I do, I undo, I redo. It was only a few minutes until she and her colleagues were due back at their office, but they were gripped by the expressions of the visitors who made it to the top.
"I came because I saw it on television, and because I work down the road, but I'm seriously impressed," Ms Amarteifio, 27, a finance project co-ordinator of south London said.
"At traditional exhibitions you walk around quietly, but this is noisy, lively. I like the interactivity of it. Everyone seems enthused."
Her colleague, Fraser Milne, agreed. He could have watched people going up and down all day. "I prefer it to the Dome... there you were indifferent to the exhibits. Here [he gestured at the giant spider behind him] you love it or you hate it."
After all the fanfare and hype of grand openings and celebrity-studded parties, yesterday the real test of Tate Modern began. Would the public want to go? Judging by yesterday's turn-out, it does.
In the Turbine Hall it was hard not to feel awed by the sheer variety and scale - not of the exhibits, but of the crowds of people who came through its doors. From 5am they had come, young, old, from south London and South-East Asia, squashed into pushchairs or clutching train tickets back to the Cotswolds.
By lunchtime some 6,000 were moving slowly but good-humouredly through the galleries, voices raised in distinctly unBritish animation, as staff, some still a little peaky from the previous night's celebrations, stood and handed out leaflets.
That night, Tate Modern had been filled with the movers and shakers of the art world, the exotically clad Ã©lite, all eager to be associated with the biggest artistic happening in decades. Yesterday, they came for purer reasons; not because they wanted a little of that glamour to rub off on them, not even to be first in (that award had gone to Andy Eathorne, a boat builder, with his pre-dawn backpack and Thermos), but because they were curious, and interested, and because there seems to be a popular view that modern art "is exciting".
Tate Modern has come to symbolise a renaissance among London's artistic institutions. With the National Portrait Gallery's new Ondaatje Wing, the National Maritime Museum's Neptune Court, and the revamped Guildhall Gallery and Courtauld Collection, as well as less cultural phenomena such as the already much-loved London Eye and even Mile End's Millennium Park, there seems to be a new determination to make the capital a worthy competitor to the delights of such cities as Paris and Barcelona.
Yesterday, in stark contrast to the bad-tempered queues that characterised the Dome's first few days, visitors did not seem to mind that it was too crowded to get a proper look at many exhibits.
They did not mind that they had to queue for the interactive sculptures. They did not even seem to mind that in order to get a drink from the cafÃ©, they had to negotiate a queue that by lunchtime was almost 200 people long.
It might not have been much of a substitute for roast tomato soup and charred, cornfed chicken, but manager Duncan Ackery was working the queue, handing out cups of mineral water and charming the hungry. Tate Modern, he admitted, had been a little surprised by the number of visitors on its first day. "But the nice thing about working in a gallery is that people are in a good mood when they come," he said.
They were also a little taken aback in the gallery shop, where the payment system was spluttering under the numbers of customers clutching "Modern" mugs (£5) and Tate handbooks (£3.50), the day's biggest sellers. The discerning could also choose from Tate gingerbread biscuits, T-shirts or chocolate, all adorned with the distinctive Bankside silhouette. Budding Nicholas Serotas could even Make Their Own Tate Modern for a modest £4, some £134m less than the original. Everyone, it seemed, wanted proof that they had been there, seen that.
But away from the souvenirs and the "modern British menu", the real key to the gallery's future lies in its ability to bring modern art to the masses. And if 17-year-old Karen Hussey and Leighanne Yeoman, 19, of Nottingham, were anything to go by, this is where Tate Modern will triumph. The fact that it was free, they agreed, was crucial. But its beauty, they said, was that it does not intimidate.
"The entrance is really welcoming; you don't get smacked in the face by artworks straight away.
"It's not so daunting for people who don't understand it," said Ms Hussey.
Her father, an accountant with "little interest" in art, had watched the opening with her the previous night on television. "He thought it was really interesting. He liked the spider," she said. "I even think he'll come with me next time."
Ms Yeoman said: "I can't wait to see the Rothkos. I've been so excited all week. But the thing is, you don't need to be interested in art to come and like these things."