Over the past seven years Prague has been constructing The ‘Tunel Blanka’ a 6.4km motorway tunnel under the whole city. This makes it the longest road in Prague and the longest city tunnel in Europe. It’s also all downhill (depending which way you are going). While it hasn’t yet opened to the public Blanka has attracted the use of a group of skateboarders and has hosted some interesting sessions, though the ride will end soon in December when the tunnel is open for drivers.