This city was settled by anglican english people in the main so it was a designed city so has a lot of geometric designed streets.
There are a lot of classic architectural buildings in CHCH including "The Cathedral" in "The Square" which is the center of the city.
The ship docks in Lyttelton (CQ2 zone) which is in an extinct volcano and is separated from the city by the hills of the crater.
The city is approx. 12Kms from the port and the road to the city goes via a 2 Km tunnel through the hills with no walking paths. (vehicles only)
You could however take the settlers track which goes over the hill and would only be suitable for "fit" people as it is quite tough and you would still have an 10K walk to the city.
On the other side of the hill is a gondola ride to the top which provides a great view's of the "Canterbury Plains" all the way to the "Southern Alps" (backbone of the South Island) on a good day.
The US air force runs their support system's for their and our Antarctic bases through CHCH airport called "Operation Deep freeze", I think?
There is also a visitors center in the area to experience what it is like down in Antarctica including a penguin house and a Snow vehicle extreme ride.
Here is a Lyttelton search page