Almost a quarter-of-a-million people have filed through Banksy's homecoming exhibition since it opened in June.
Bristol's council-owned gallery has been overwhelmed with visitors, with some people queuing for up to four hours to see Banksy vs Bristol Museum.
"We knew it was going to be big but I don't think we appreciated just how big," a council spokesperson said.
The graffiti artist's show, featuring animatronics and installations, was kept secret until the day it opened.
Banksy draws the crowds in Bristol
Demand to see the show has been so high that queues continue to snake almost a mile every day, and the museum has arranged for late-night opening on a Wednesday.
The museum is in talks with Banksy's team about further late night openings until the exhibition closes on 31 August.
"The exhibition has drawn in people from around the world," the spokesperson added.
"It's not just local people and visitors from the UK who want to see this. We have had people from all over, including Finland, Japan, New York and even Uzbekistan."
When the exhibition first opened in Bristol queues of up to an hour were the limit, but as it nears its end even more visitors have been flocking to see it.
The queue was closed early on Saturday as visitors waited four hours
The queue was closed at 1230 BST on Saturday as the waiting time peaked at four hours.
With a 650 capacity in the gallery, organisers are operating a two-in-two-out policy.
Nigel Megitt, from London, was one of thousands of people who queued on Saturday.
He joined the queue at 1030 BST, and made it into the gallery at 1430 pm - four hours later.
"We went along expecting a long queue, so we were prepared," he said.
"We took a newspaper, and one of us was able to leave the queue to go to the shop and buy food.
"It was part of the day, part of the experience, and you have to be prepared to queue if you want to see the exhibition."
The council spokesperson added: "Managing the queue has been a challenge, but the best thing is that people have been very good natured.
"Even though people have had this huge wait, people have said the exhibition, with its quirky and challenging pieces, is amazing."