Invisible Cities, the social enterprise operating  in Cardiff, Edinburgh, Manchester, Glasgow and York  Invisible Cities – Train people who have previously  experienced  homelessness, to become walking tour guides of their own city  – is inviting supporters, friends, customers and partners to take part in a virtual mile-covering challenge, to celebrate Invisible Cities turning 5.  Running from April until July there are 4 legs (one per month) that collectively make-up 500 miles as participants virtually move between Invisible Cities locations. Participants are invited to sign up for one leg, or all 4 and the challenge is to complete…