The summer season in one of Bulgaria's northernmost seaside towns kicked off as it should on the northern seas - apocalyptic - with a Finnish touch of cello strings and a crowd of fans gathered for the Apocalyptica concert.

The band's gig in the town of Kavarna was one of the first legs on the European summer festivals tour to promote Apocalyptica's latest album Worlds Collide and their fifth concert altogether in Bulgaria.

A free event, courtesy of the Kavarna town hall, the concert stage was set in the town square, rather than the football pitch used for bigger summer concerts. The square struggled to contain the couple of thousand fans that made the trip.

The concert was due to start at 8pm, but long-haired rock fans dressed in black t-shirts, jeans and overcoats flocked to the square five hours earlier to make sure they would get a first-row experience of this utterly original, in every respect, music of genre-shattering metal sound. Their dedication to the cause was rewarded with the opportunity to observe a rare sight - the Apocalyptica sound check.

Staying true to the string instruments theme, the organisers have invited Bulgarian female quartet Strings to warm up the crowd for the Finnish headline act. The four ladies staged a good performance, backed up by a rock band of young musicians to harden the sound of the two violins, one viola and a cello. Strings managed to settle the mood and provided a smooth transition to the next level - Apocalyptica.

After a short break to set the stage, cello virtuosos Eicca Toppinen, Paavo Lötjönen, Perttu Kivilaakso, drummer Mikko Sirén and session musician Antero Manninen appeared on stage to take their seats on the appropriately designed chairs in the shape of violoncello-shaped skulls.

Bringing some northern spirit, Apocalyptica opened with Worlds Collide to warm up the audience. The sound wave swept away any lingering doubts about the quality, and volume level, of the sound and the attending crowd eagerly cheered the band on. What followed next was a long procession of perfectly-executed instrumental pieces, with the band visibly content and enjoying themselves. Occasional desperate cries from young females, who screamed Eicca's name, only added to the atmosphere of a true rock concert.

In between Helden and Under the Hall of the Mountain King, Toppinen and Kivilaakso jumped from their seats to get closer to the edge of the stage and headbang, creating a vision of blonde and black halos above the two cellos, never missing a single note of whichever song they were playing. After a couple of songs, Lötjönen also left his place and joined his band mates. As expected, Manninen remained seated, his sunglasses on his eyes, maintaining a stony face.

Apocalyptica played Bittersweet - a piece that features vocals from fellow Finns Ville Valo of HIM and Lauri Ylönen of The Rasmus in the album version - and the audience did not miss the chance to sing along. The set list included a mix of original Apocalyptica instrumental pieces and covers of heavy metal songs, among them I'm Not Jesus, Seemann, Somewhere Around Nothing, Life Burns and Sepultura's classic Refuse/Resist. Throughout the concert the band and the audience exchanged the usual objects - t-shirts flying towards the stage and drum sticks from it. A single rose also made its way onto the stage and had its five minutes of glory as band members passed it among themselves.

After thrilling the audience for more than one hour with their exquisite bow and cello strings set, the five musicians left the stage, only to appear two minutes later, when the audience started chanting the customary "We want more!" and the band's name. The first comeback included Metallica's Nothing Else Matters - the song that earned Apocalyptica acclaim for more than just a cover band. The second comeback included another old Metallica favourite, Seek and Destroy.

The third, and final, comeback marked the end of the concert with the band members bowing out at the end of the show. Apocalyptica looked visibly pleased by the reception they got and even Antero Manninen cracked a smile at the screaming crowd just two meters from the stage.

The free-for-all concert on May 31, organised by Joker Media and Kavarna mayor Tsonko Tsonev, who has earned the moniker of "the metal mayor" for his love for hard rock and persuading big-name bands to play in the small town, was also different from most events of its kind in that fans were allowed to take photographs throughout the concert.

In the end, not all Apocalyptica fans are as lucky, even at other open-air festivals, the tickets for which, in some cases, have already been sold out.