A heavy metal sound with an orchestral arrangement – four cellists from Finnish heavy metal band Apocalyptica have performed in Moscow and St. Petersburg as part of their world tour.

Their mastery of the cello is an open ticket into any orchestra, but they've opted for an altogether different path. One day, the four Finnish classically-trained cellists decided to experiment and instead of their usual classic numbers, played songs by heavy rock band Metallica.

They found this unexpected take on the metal band got a good reaction and now they get big audiences around the world.

Soon the band was invited to support their idols during two Metallica concerts in Helsinki.

“They like us but it's kind of weird. But that's such a nice thing to hear that they appreciate things that we've done with their music, that's the nicest thing to hear. We have been jamming together with them – and they're very down-to-earth guys, which is very cool,” Perttu Kivilaakso from Apocalyptica said.

Apocalyptica are frequent performers in Russia. They've played six concerts here over the last few years. The warm welcome they get is why they keep coming back.

“Yesterday we played in St. Petersburg and once again proved that the Russian audience is the most passionate audience in the world!” Kivilaakso said.

But they do not just want to be playing Metallica. They have branched out and made their own compositions, but fans will continue to be able to enjoy heavy rock with strings.