Nos. 1, 10 (originally 9), 15 (originally 8 ), 17 and 18 are essentially the same. Raynor used the inside of the property, except the polo field, which is the practice range today. Macdonald's layout was clockwise going out (with OB on the left), counter-clockwise going in.
You'll be hard-pressed to find a more testing start than the first three holes.