Classic first-visit walk
Start with Berlin's symbolic gate, then let the street get denser: Bebelplatz, Humboldt University, Neue Wache, Schlossbruecke and Museum Island.
U-Bahn fallback
U5 Brandenburger Tor, Unter den Linden or Museumsinsel.
Best pause
Bebelplatz if the square is calm; Museum Island if you want the best ending.
BerlinWalk fit
Best before or after the 2 hours tour, not as a rushed detour during it.
Tip: do not spend all your time at the Brandenburg Gate. The strongest part of Unter den Linden is the sequence of smaller stops east of Friedrichstrasse.