Now this is a MUCH better walk than the over-hyped Spit Bridge to Manly Walk. This walk has better views, and goes through a former school of artillery and several different types of terrain. Really amazing views of the city in the distance.
The walk starts from Manly and goes to North Head via North Head sanctuary, and then comes back round to Manly. Some of it is backtracking from North Head, but after the artillery school you can come back a different way to Manly.