This is the famous Hermitage in St. Petersburg, Russia. I used a 16mm wide angle, and because of the significant keystoning in the original image, I used Edit > transform > distort to straighten the columns. Because of the crowds, I had to wait quite a while to get a shot without people. Even so, I did clone out four tourists. I had photographed my wife in a costume she made in Venice, so I selected her with the quick selection tool in Photoshop and pasted her into the stunning interior, sized her correctly with Edit > transform > scale, moved her into place with the move tool. I then used the burn tool to create the subtle shadow beneath her dress. Finally, I selected the shih tzu puppy that I'd photographed against black velvet using the 'select and mask' feature plus refine edge. I placed it behind the dress to drive home the illusion the dog was really there. My settings for the interior were 1/125, f/6.3, and 1600 ISO. Lastly, I used the burn tool again to make a small shadow under the puppy. Everything casts a shadow, even in diffused light.