More than 120,000 people - a record for an Australian art exhibition at the National Gallery - have attended and another 10,000 were expected over the holiday break.

The gallery has even brought in a new oil painting just for this weekend.

National Gallery of Australia assistant director Adam Worrall said the painting was acquired only last week from a private collector in South Australia.

The small oil work was painted in 1884 when Roberts visited London, and is called The Thames and Cleopatra's Needle.

It was a piece Roberts kept with him his entire life, and was still in his house when he died.

"It's the first show that we've ever done that really brings together a group of national images of Australia," Mr Worrall said.

Paintings depict places many Australians see everyday such as Mentone and Coogee beach.

"They're places that don't look any different today, except for the buildings that are in the background, the natural coast land is in exactly the same spot," Mr Worrall said.

Among the 120,000 visitors, more than 70 per cent were from interstate, which was the highest visitation of regional Australians the gallery has had for a show.

"I've met so many people from regional NSW and Victoria that have got in their car and driven for four to six hours to come and see this exhibition," he said.

Expect this weekend to be a busy one since Canberrans have a reputation for going to exhibitions at the last possible opportunity.

Buy tickets online to skip the queues and on recommendation from Mr Worrall, lunchtime and post-3pm are usually the quietest times.

The exhibitions ends on Monday.