Listed clockwise from Main North Road, the inner route consists of:[1][5] The Inner Ring Route is adjacent to the outer edge of the Adelaide Park Lands except on the western side between Anzac Highway and Port Road where railway lines occupy the space along the parklands, and the road ring route is further out.

The earlier A21 route using West Terrace passed inside the ring of parklands instead.

The Park Terrace section had a level crossing of the Outer Harbor railway line until 2017.

The crossing was replaced by a bridge when the railway was lowered as part of a project to separate the Torrens Junction so that suburban trains to Outer Harbor did not conflict with interstate trains on the standard gauge line.

In 2017, it was named after the engineer who supervised its construction, David Fitzsimons.