30 Seconds to Mars Play Surprise Gig on Roof of O2 Arena in London to Support their 2013 Tour of Europe

30 Seconds to Mars have gone sky high. The alternative rock band played a rooftop gig in London June 18 to support their upcoming U.K. tour.

According to NME, the group climbed the side of the O2 Arena in England's capital before playing a four-song set to a small, intimate audience. Lead singer Jared Leto joked to the crowd that he was able to "exercise and get a free show" and hinted that they may just parachute down to the ground (of course, they did not).

The set included two songs off their latest album Love, Lust, Faith & Dreams, "End of All Days" and single "Up In The Air." 30STM also played hit "Kings and Queens" and "Closer to the Edge," as per a fan's request.

30 Seconds to Mars have been popping up in guerilla-style promos all over London. They recently had a flashmob show in the city's SoHo Square. That surprise gig had a larger audience present than the one on top of the O2 Arena. Watch a video of the group playing "Up In The Air" in SoHo below:

Leto explained the unexpected, unusual shows at the rooftop performance. "We try not to do the typical bulls**t; we try and do a different brand of bulls**t," he said. "We probably won't forget this for at least a few days."

Later on he added, "It's great to do something different for all of us. It breaks up the monotony and the onslaught of information that gets released into the universe now. It's a fun way to celebrate a new tour."

30 Seconds to Mars are in the middle of a European tour right now to promote their new fourth studio album.

It's unclear when the group will play across America in support of Love, Lust, Faith & Dreams, though a show at Los Angeles' Hollywood Bowl is scheduled for Oct. 12.