Can Dachau and Hitler's Eagle's Nest be seen in one day? Also, is there a way to get to the Eagle's Nest from Garmish Partenkirchen.
Following on from Lee, the fastest trains are 4 and a half hours, and you then have to still get up the mountain.
Not practical in one day; both highly valuable destinations deserving sufficient time -- otherwise why go?
I guess you could go to the gates of Dachau, say "Dachau, check" and then go to Berchtesgaden, take the regular bus to Hintereck and the mountain bus to the Eagles' Nest and say "Eagles' Nest, check", but with the time between them (about 4 hours) you couldn't do either one justice.
Tours of Dachau take about 2½ hrs and go off at 11 AM and 1 PM. That pretty much takes the middle out of the day.
I spent a full morning at Kehlsteinhaus (Eagles' Nest), had lunch there, then came down to Obersalzberg and spent the afternoon at the Dokumentation Center.
The fastest way by train from Garmisch-Partenkirchen to Berchtesgaden would be through Munich Hbf.