Possible Clues:

• Art form in the Vatican's Raphael Rooms
• Key on ring beneath father’s painting
• Michelangelo's "The Last Judgment," e.g
• Painting for excursionists, Canaletto with selection of exteriors
• Type of wall painting
• Method of painting on walls
• Art on wall forces demolished
• Slave turns up with company artwork
• Officer commanding lowly worker to bring back work of art
• It's about counsel inside of what's up on the wall