Some are unmissable, made from 6” tiles in colours that shout out across the street. Others are small and subtle, a gift to the observant passer-by who happens to look up (or down) at the right moment. Those are the Space Invader mosaics I like the best. Here (above) is a recent sighting in the eighth arrondissement, just round the corner from the Élysée palace.  Down below there’s a shy beastie from Menilmontant and a couple of invaders seen last summer, in Croulebarbe and Montmartre.