Every time I start to lament that all the great summer events are over and there is such a long wait until the Christmas season starts, I realize that smack dab in the middle is that spectacular Berlin show: The Festival of Lights. A precursor to the holiday market rounds, the Festival hits usually around the same time as the brisk shift in weather, requiring one to bundle up tight in order to withstand chilling nighttime temperatures and tour the light shows. Sometimes a shock to one's fresh-off-summer sensibilities, it's still quite a show.
If you haven't made it out to see any illuminations this year, I highly recommend at least making the stroll from the Berlin Cathedral down Unter den Linden to the Brandenburg Gate and Potsdamer Platz. They are indeed different from last year, with the Humboldt University display (first photos below) my absolute favorite this time around. Pack a bottle of something strong or be prepared to buy a few coffees along the way to keep the blood flowing. Trust me, it's worth it.
For more information, see the festival website and map of illuminations