ROME (AP).- Italian police have recovered hundreds of ancient artifacts in their latest effort to crack down on the looting of art, and have looted art, and they chose a unique setting to display them Friday: the Colosseum. The 337 pieces displayed in the ancient Roman arena include vases, bronze tools and marble statues of Venus, some dating as far back as the 8th century B.C. Police said the pieces are worth some euro15 million (about $20 million) overall. They said the pieces were returned from Switzerland in June after a two-year investigation. Italy has aggressively pursued the return of art it says was illegally looted from its soil and sold to museums or private collections worldwide. This probe grew out of an investigation into an Italian art dealer later convicted of art trafficking. The objects were seized in Geneva, part of a massive haul of some 20,000 artworks from