Watch a flash mob of 150 musicians cover Green Day's Boulevard of Broken Dreams

Hard-rocking flash mobs are nothing new. In recent years, we've seen hundreds of guitarists, bassists, drummers and singers team up to cover classics by Nirvana, Metallica and Rage Against the Machine.

Famously, a 1,000-strong ensemble in Cesena, Italy so moved the Foo Fighters after their cover of Learn to Fly went viral that the Dave Grohl-led group went on to play a show at the small city.

Still, these mass covers are always a delight, and a new one – which brought 150 musicians together at Bánffy Castle in Bontida, Romania for a version of Green Day's Boulevard of Broken Dreams – is no exception.

You can check out a professionally-shot video of the performance below.

The group was assembled by CityRocks, a group that calls itself "the biggest rock band in Central Europe." Aside from the aforementioned Nirvana and Metallica covers, the group has also tackled classics by the likes of Linkin Park, blink-182, Bryan Adams and many more.

For their part, Green Day are fresh off a new single, Holy Toledo! An infectiously bouncy pop-punk number of the highest order, the song features prominently in the soundtrack of the film Mark, Mary & Some Other People.

It was the band's third stand-alone single of 2021, following Here Comes the Shock and Pollyanna.