Sydney’s harbour is a ria — a river valley drowned when sea levels rose after the last ice age — which is why it is so intricate, with 240 kilometres of shoreline folded into bays and headlands.
The city is arranged around it, and the water is why nothing here is quite where a map suggests.
The shape
The CBD sits on the southern shore at Circular Quay, where the First Fleet landed in 1788, with The Rocks to the west and the Opera House on Bennelong Point to the east.
The Harbour Bridge crosses to North Sydney and the Lower North Shore.
Running east: Woolloomooloo, Potts Point, Darlinghurst, Paddington, and out to the eastern beaches — Bondi, Tamarama, Bronte, Coogee.
Running south and west: Surry Hills, Redfern, Newtown and the Inner West, and eventually Parramatta, 25 kilometres out and the geographic centre of the metropolitan area.
The Northern Beaches run 30 kilometres north from Manly to Palm Beach.
Scale
Around 5.5 million people across the metropolitan area, spread over 12,000 square kilometres — one of the most sprawling large cities in the world.
For a visitor, almost everything is within eight kilometres of Circular Quay, and the ferries, trains, metro and light rail all radiate from there.
The land
This is Eora country, and the clan of the southern harbour shore is the Gadigal. Aboriginal people have lived here for at least 30,000 years and Aboriginal Sydney is not a historical topic — the city has one of the largest urban Aboriginal populations in Australia. See The Gadigal, and what happened here.
The population
Around 40 per cent of Sydney residents were born overseas and roughly the same proportion speak a language other than English at home — chiefly Mandarin, Arabic, Cantonese, Vietnamese and Nepali.
The city’s food, its suburbs and its politics all follow from that. Postwar migration from Italy and Greece, then from Vietnam and Lebanon, then from China, India and Nepal, has shaped it more than anything else since 1945.
The climate
Humid subtropical. Summer (December to February) is 19 to 27°C and humid, with days above 35 and occasional extremes well past 40 when hot air comes from the west. Winter (June to August) is 8 to 18°C, dry and often brilliantly clear.
Rain falls year-round with an autumn peak, in short heavy bursts rather than drizzle.
The UV is extreme, which is the thing visitors most consistently underestimate.
Language
English, with an Australian vocabulary that takes a day to absorb. Arvo is afternoon, servo a petrol station, bottle-o a liquor store, thongs are flip-flops, doona a duvet, capsicum a pepper, and how are you going is a greeting rather than a question about transport.