Over the past five years, one in four inner-city music venues have closed down. To combat the culling of music venues in the city centre, Clear Channel Sweden has taken over Stockholm's metro station to promote 'underground' music. As the out-of-home (OOH) sector leads the development of 'smart cities' through technology, Clear Channel is working to slow down that reality by allowing its billboards to add new functions to serve its residents. It therefore wanted to find a way to provide a solution to the global night economy. Instead of displaying ads on Clear Channel's 300 digital screens, the 'Stockholm Underground' music guide, will run as a real-time guide to encourage commuters to take advantage of local shows and up-and-coming artists performing at smaller venues.Drawn from a database of upcoming live shows aggregated from online sources such as websites, blogs and Facebook events, with up-and-coming bands and artists also able to add their shows to the database, the initiative will give even the smallest acts a chance to reach up to one million people. The data will then be used to direct commuters to their nearest local music show in the hours before it is supposed to begin.Running for three weeks, Clear Channel says the technology can be transported to other cities who are similarly experiencing the same problem. In London, 35% of grassroots music venues closed down between 2007-2017, while in Australia, a parliamentary inquiry found Sydney was experiencing a 'music venue crisis.'