Paris has 173 museums, with countless temporary exhibitions and events held weekly. The most popular venues draw huge crowds and long lines making pre-purchased tickets and museums passes essential. Beyond traditional museums, the colossal Palais de Tokyo and the 104, a converted city morgue, are dynamic contemporary art spaces. Galleries welcome visitors with a concentration of traditional art in the St Germain des Près area and contemporary collections in the Upper Marais. For the adventurous, the street artist Invader sells maps featuring the thousands of arcade game character mosaics he has put up across the city. More street art is encouraged on the rue Desnoyez in the 19th, attracting graffers from across the globe.