As they excavated parallel tunnels under the city to create the Cityringen metro line with 17 elegant and colourful stations around the historic centre of Copenhagen, the tunnel-boring machines (TBMs) went below the foundations of old buildings without putting any of them at risk. Indeed, one of the stations was dug right under the Marmorkirken. Founded in 1894 as a Lutheran place of worship, it is one of the most imposing structures of the Danish capital, with a dome inspired by Saint Peter’s Basilica in Rome. It is also the largest of its kind in Scandinavia.

During works, carried out by Webuild, the prior was not in any way worried: “Every day the sound of the boring machines make me jump. Let’s hope that the Church withstands the vibrations. Then I tell myself: I have faith in God and, to tell you the truth, I trust these men – they know what they are doing.” The station, built 30 metres below the church, is the deepest of all stations.

Delivered in 2019, Cityringen comprises 31 kilometres of tunnels under the city centre. Its creation did not stop Danes from going about their business despite the rumblings of the TBMs, the trucks and cranes and movement of excavated earth. It has also helped Copenhagen in its goal of being able to declare itself the first carbon neutral capital in the world. That is because 85% of its residents have come to have a public transport service up to 600 metres from their homes. So their vehicles can stay in the garage. According to official figures, the line serves at least 240,000 people every day.