This is one side of the magnificent gateway of the Pergamon Altar of Zeus inside the museum. This famous Hellenistic altar (180-160 BC) is from Pergamos in Western Turkey. Discovered in 1865, it was removed from its original location beginning in 1879 by agreement between the German and Ottoman empires. German archeologists excavated the site and then partly reconstructed the altar here in Berlin, where it has now become one of prize possessions of the Pergamon Museum.
The entire structure once stood forty feet in height atop the acropolis of Pergamos. It had a frieze about 120 meters long and featured a depiction of a battle between the Greek gods and giants.
This theme comes from Greek mythology and was used here to celebrate the defeat of the Galatians by the kings of Pergamos. More than 100 figures can be seen in fierce combat.
The altar has also been a source of national pride and inspiration to several German national regimes, and Hitler wanted the grand review stand at the Zeppelin Field in Nuremberg designed to resemble it.
I didn't get a complete shot of the entire altar, but you can see views of the complete structure on this page, which also provides some more background on the art, history, and mythology behind the Altar.
Pergamon Altar side