Complex sentence: As proof of the veracity of Elizabeth's message, the Doctor is shown a 3D painting made by Time Lord using "stasis cubes" and depicting the fall of Gallifrey's second city, Arcadia, on the last day of the Time War.
Split into simpler sentences: As proof of the veracity of Elizabeth's message, the Doctor is shown a three dimensional painting made with Time Lord stasis cubes. The painting depicts the fall of Gallifrey's second city, Arcadia, on the last day of the Time War.