The Rottweiler is a robust working breed of great strength descended from the mastiffs of the Roman legions. A gentle playmate and protector within the family circle, the Rottie observes the outside world with a self-assured aloofness. A male Rottweiler will stand anywhere from 24 to 27 muscular inches at the shoulder; females run a bit smaller and lighter. The glistening, short black coat with smart rust markings add to the picture of imposing strength. A thickly muscled hindquarters powers the Rottie's effortless trotting gait. A well-bred and properly raised Rottie will be calm and confident, courageous but not unduly aggressive. The aloof demeanor these world-class guardians present to outsiders belies the playfulness, and downright silliness, that endear Rotties to their loved ones. (No one told the Rottie he's not a toy breed, so he is liable plop onto your lap for a cuddle.) Early training and socialization will harness a Rottie's territorial instincts in a positive way.
 
Read more at https://www.akc.org/dog-breeds/rottweiler/