-->Railway to Dachau:
Use urban railway S2, exit Dachau
-->From Dachau station to Concentration Camp Memorial Site:
Bus line 724, terminal station Kraeutergarten, exit Memorial Site parking lot
Bus line 726, terminal station Saubachsiedlung, exit Memorial Site main entrance
-->From Dachau station to center of Dachau Old Town:
Either Bus line 720 or 722, both exit Rathaus (cityhall), line 720 is direct and much faster
-->From Memorial site to center of Dachau Old Town:
Bus line 724, transfer at Ratiborer-Str. to line 722, exit Rathaus
Bus line 726, transfer at J.F.Kennedy-Platz to line 722, exit Rathaus
It's also possible to go straight back to railway station with either line 724 or 726, and use line 720 from there to Old Town.
This of course may take a little longer, but as all lines connect at railway station, one can't go wrong.
-->From Memorial Site back to railway station:
Either Bus line 724 or 726, both exit at S-Bahn station
-->From Rathaus back to railway station:
Either Bus line 720 or 722, line 722 is direct and much faster
Use own car:
-->From Munich, using main roads:
Orient in Munich to Dachauer-Str., drive straight on it always city-outward, on the connection road from Karlsfeld to Dachau, use the junction to B471 (Bundesstrasse, major road), direction Hochbrueck/Oberschleissheim, exit B471 at interserction Bajuwaren-Str., turn left on Bajuwaren-Str. direction Dachau-Ost/Hebertshausen, drive straight over the crossing Schleissheimer-Str. to Alte Roemer-Str., find the Memorial Site after 1000 meters on the left side.
-->From Highway A9/A92, Deggendorf-Salzburg-Nuernberg-Munich:
Use highway exit Oberschleissheim, orient direction Dachau, in Dachau after the first circular traffic, turn the next street right, this is already the Alte Roemer-Str., Memorial Site is after 1000 meters on the left side.
--From Highway A8, Munich-Stuttgart:
Use highway exit Dachau, this exit connects to B471, drive it direction Dachau, exit B471 at junction Dachau-Ost, exit B471 at interserction Bajuwaren-Str., turn left on Bajuwaren-Str. direction Dachau-Ost / Hebertshausen, drive straight over the crossing with Schleissheimer-Str. to Alte Roemer-Str., find the Memorial Site after 1000 meters on the left side.
-->From Memorial Site to Dachau Old Town:
Shortest way is driving Roemer-Str. direction Bajuwaren-Str., on crossing Sudetenland-Str. turn right into Sudetenland-Str., always go straight in Erich-Ollenhauer-Str., after going through an railway underpass turn left on Freisinger-Str., always straight on the main road into Mittermayer-Str., after 500 meter on Mittermayer-Str. turn left into Augsburger-Str. You're in Old Town of Dachau.
Parking space in the Old Town itself is sometimes not available for busses. More parking lots can be found in the area of Brucker-Str.