Construction engineers in Japan have broken through to make the world's longest land tunnel, as part of an extension to a high-speed rail network.
The last metre of bedrock was blasted away on Sunday
The tunnel, under a mountain in the north, is 26.5 km (16.5 miles) long.
The tunnel is unlikely to hold the record for long as two longer tunnels are due for completion in Spain and Switzerland over the next two years.
Critics say the tunnel, which costs more than $600m (£313m), will not be financially viable.
The northern regions around the new link are only lightly populated.
The BBC's Jonathan Head in Tokyo says Prime Minister Junichiro Koizumi has made curbing the country's addiction to concrete one of his central policy objectives.
But government borrowing has actually increased over the past four years - partly because tax revenues have been falling as the workforce shrinks and partly as a result of the back-log of high-cost infrastructure projects approved many years before.
At a ceremony on Sunday morning, the governor of the northern Aomori prefecture, Shingo Mimura, pushed a button to blast away the last 1m-thick bedrock in the Hakkoda mountains.
The tunnel will now have to be reinforced with concrete, and tracks laid.
The project to extend the bullet train to Aomori has been an expensive engineering challenge, our correspondent says, which has required digging two record-breaking tunnels under the mountains.
The railway extension will take seven more years to complete.
Critics have complained that the project is a waste of money, as Aomori is a lightly populated area - they argue that two giant undersea tunnels built in Japan in the 1980s at a cost of many billions of dollars have done little to lift the economies of the areas they connected.
But the central government still faces strong lobbying to fund new infrastructure, because many of Japan's depressed regions can think of no other way to revive their economies.
The previous record, set in 2002, was a 25.8-km tunnel for a railway line in a neighbouring prefecture.