The modern Rottweiler today is very different looking from the dogs that accompanied the Roman Legions and from the dogs they left in the old German City of Rottweil in Wurtenberg, Western Germany, that came into contact with dogs native of the area and the natural result was an interbreeding of the breeds of the area making the breed we now call The Rottweiler.
 
Although The Main characteristics of the breed remain along with its black and tan markings, the overall look seams to be very different at least from the dogs of the turn of the 20th century.

The breed standard has changed as it does with all breeds, white on the chest is now a fault, it was normal once (aloud 80 years ago) but the standard still call for a construction and temperament for a working dog, that still worked in many European countries today.  

Evolution 3

Female Rottweiler
(deceased)1907
 grand mother to the dog below

Evolution 5

Male Rottweiler
1911 (deceased)
Height 28.25"
sire of the dog opposite

Evolution 9

Male Rottweiler
1929

great great great grandad to dog below

Evolution 2

Male Rottweiler
1918
Breeds greatest producer until
Bulli v. Hungerbuhl.
Sired over 100 litters
His parents were litter mates
Good example of strong In-Breeding

Grandad to dog opposite

Evolution 8

Male Rottweiler
1943

Evolution 4

Male Rottweiler
1957
Int'l/Am CH
First dog inducted in the MRC Hall of Fame