The tavern, built on the Auckland waterfront as the Rob Roy Hotel, is being moved to allow a new motorway tunnel to be built before it is shifted back to its original location after six months.
Hydraulic rams began shoving the 600-tonne brick building along four concrete beams about 7.30am today and had moved it just 12 metres by 4pm.
Design engineer Adam Thornton said progress had been slower than anticipated. It was expected to be relocated before the day was through, but it would now take until at least midday tomorrow.
The Teflon-coated concrete beams it was sliding on were crossing moderately compounded ground, so it was possible they could sink a bit, he said.
For this reason, the building's levels had to be monitored constantly and hydraulic jacks had been fitted which could lift the building if necessary.
"It only needs to drop about 10 millimetres for it to crack," Mr Thornton said.
"But it's all going to plan in terms keeping it nice and level, even though it's taking a little longer than expected, but it doesn't matter - we'll take as much time as is necessary."
In preparation for the move, engineers put reinforcing steel rods through the bricks and reinforced concrete on the rear concrete wall. Carbon fibre strips were also inserted in the old hotel's chimney to provide seismic strengthening.
Helen Cook, of the Victoria Park Alliance, estimated at least 2500 people had stopped to look at the building inching its way up the hill.
"They care because it's an iconic building in this part of Auckland. But we were actually surprised to see how many people came to see it and how delighted they are to see it saved, and to see what is probably an engineering milestone," she said.
When the Rob Roy was built on the Freeman's Bay waterfront in 1886 it was in "a real slummy area, quite separate from the rest of the city", said New Zealand Historic Places archaeologist Bev Parslow.
"It was almost on a little island, a heavy industrial area, a working-class industrial, residential area.
"There is very little of the 19th century landscape left there."
She said the hotel was a fascinating part of Auckland history.
