Lyttelton was established as a seaport in the late 1840's. It provides a safe, sheltered, deep water harbour as it lies in the caldera of an extinct volcano. The town's steep streets are a novelty for many Christchurch drivers, who rarely encounter a hill (unless they deliberately drive to the hill suburbs on the edge of the city).
In the early years, Lyttelton provided a transshipment point for cargo bound for Christchurch. Passengers and light cargo would travel over the Bridle Path on foot or horseback. While heavier cargo was shipped in shallow draught coastal vessels back around the coast, across the treacherous Sumner Bar and into the Estuary to Ferrymead or, later, Steam Wharf, just down the Heathcote River from where the Tunnel Road meets Ferry Road.
There are three ways by car from Christchurch into Lyttelton:
Through the Lyttelton Road Tunnel. The Tunnel is probably the best bet if you're unfamiliar with driving on the left and squeamish about steep twisty turns on hills. Although New Zealand roads are pretty good and you do get a great view going over the hills.
Over the Port Hills along Dyers Pass Road (past the Sign of the Takahe)
Via Gebbies Pass, though this is a rather indirect route and is probably only a practical alternative if southwest of Christchurch.
Lyttelton Farmers Market is an authentic farmers market in the School grounds every Saturday morning, 10am-1pm. Not necessarily the cheapest food in town, but always fresh, local, and seasonal. Food available ranges from fruit and veggies to bread, coffee, home-baking, farm eggs, local honey and cheeses, preserves and relishes, etc, etc. There is usually some live music and always a lively collection of marketgoers, great people-watching.