Last year's event – won by Samsung Galaxy White – was held in Seoul's Sangam Stadium in South Korea after group stages in Taipei, Taiwan and Singapore. This season's promises to be similarly geographically varied with Riot's blog explaining:
"Worlds 2015 will be a multi-city, multi-country event -- with our Group Stage, Quarterfinals, Semifinals, and Final showdown held in different cities within Europe."
As to which cities Riot means, they're keeping that to themselves for the moment, although last year alone the company brought the LCS roadshow to Wembley in London and the All-Star to Le Zenith in Paris so there's a level of experience and proven enthusiasm for both those cities.
The blog goes on to say:
"Last year’s multi-city journey to Worlds was a fast-paced and exhilarating ride - we learned a ton about the kind of experience we want to offer to competing pros, fans in the stadiums, and viewers at home. We’re ready for an action-packed month in Europe."
The announcement comes on the eve of the LCS's Spring Split which marks the start of the professional eSports season in Europe and North America.