Which “art project” started off with these 3 postcards?

Bonus question for today. What is blacked out?

Cracked by: shrik(2), Shwetha Maiya(2), udupendra(2), Manish Achuth(2), Sumanth Patlolla(2), rohanquizzer(2), aditthya(2), Debasish(2), raklodramA(2), krudebox(2), Siddarth Pai(2), jowens(2), Riyaz Usman(2), Rogi(2), Raghuvansh(2), dineshk(2), Ananth(2), Anjul(2), Jins(2), Thejas V R(2), shrey, varun, Moju21, vinayaknp, Dibyo and Qqsachin