The painting at the beginning of the 50th Anniversary was said to be named Gallifrey Falls or No More.
Gallifrey Falls No More was a Gallifreyan landscape painting and
stasis cube, depicting Gallifrey in the final days of the Last Great
Time War. The painting specifically depicted the Fall of Arcadia on
the last day of the Time War. There were believed to be two
conflicting titles of the painting: No More, or Gallifrey Falls.
The Doctors were able to use the Statis Cube technology that was used to create the painting to save Gallifrey.
A stasis cube was a form of Time Lord art found on Gallifrey, which
the Eleventh Doctor described as a "little sliver of time" held in
perfect stasis in a frame. The result, according to Clara Oswald,
resembled a 3D oil painting.
The Doctor had to use all his different incarnations' TARDIS'es to complete the goal of sealing Gallifrey in one.
Later, having circumvented the time-lock and traveled back to the
events of the Last Great Time War, thirteen incarnations of the Doctor
came together to lock the planet Gallifrey in a stasis cube, thus
saving the planet while making it seem that the Time Lords and Daleks
finally obliterated each other.
They have changed their minds about using the Moment, and the Eleventh
Doctor disarms the device with his sonic screwdriver. Instead, they
intend to freeze Gallifrey in a moment in time, slipped away in a
pocket universe, the way the Zygons froze themselves into Time Lord
The Curator at the end stated that the true name of the painting wasn't either one of the previously contradictory titles but both of them put together, hinting that Gallifrey was indeed saved because "Gallifrey Falls No More".
Technically speaking though the painting is actually Gallifrey though because a stasis cube was a sliver of time held in perfect state. It is essentially a moment in the Time War, at the Fall of Arcadia frozen in perfect stasis. This is the whole reason why they were able to save Gallifrey because they basically took the entire planet and put it in a stasis cube and into another dimension.