Plans to dig a two-mile (3.2km) road tunnel near Stonehenge have been given the go ahead by the chancellor.
The A303, which often suffers from severe congestion, currently passes within a few hundred metres of the ancient monument.
The plan is to build a dual carriageway alternative out of sight of the World Heritage site but it is opposed by some archaeologists and environmentalists.
Rishi Sunak told the commons: "This government's going to get it done."
In his first Budget, Mr Sunak promised £27bn for motorways and other arterial roads, including a new tunnel for the A303 near Stonehenge.
He said the A303 is "one of our most important regional arteries" but has become "one of those totemic projects symbolising delay and obstruction".
"Governments have been trying to fix it since the 1980s," he said.
"Every year, millions of cars crawl along it in traffic, ruining the backdrop to one of our most important historic landmarks."
English Heritage chief executive Kate Mavor welcomed the announcement and thanked the government for its support.
"This is an important step towards finally doing justice to Stonehenge and the prehistoric landscape within which it stands," she said.
"Placing the A303 within a tunnel would transform Stonehenge, reunite the landscape and leave a lasting legacy for future generations."
Public-private funding was due to be used to finance the road, but in October 2018 then-chancellor Philip Hammond cancelled future deals using that model.
In February, campaign group the Stonehenge Alliance amassed more than 50,000 objections to the plans and delivered the petition to Downing Street.