This is a photoshop work I made with the following three pictures.
I warp the perspective of the fountain picture and use the stamp tool to remove the logo on the corner.
Then I use the magnetic lasso tool to carve out the keyboard of the piano picture I took.
Then I insert the area I carved into the fountain picture and adjust the perspective and color curve for the keyboard, then I overlay the keyboard to the fountain.
Finally, I carve out the pianist from the third picture and transform the direction to make him sit on the keyboard.
I use the blur tool to blur out the edges and use the burn tool to add some shadows on the fountain and the keyboard under where the pianist sits.