Northern Lights takes place in a world like our own, but with several historical, geographical and philosophical differences. The story begins in "Brytain", which seems to resemble the Victorian era in the England of our own world. The reliance on steam power, the subordinate position of women in society, and various traditions and fashions make the Victorian era a reasonable comparison.
The first part of the book takes place entirely in an old university city which retains many of the features of the Oxford in our world.
Oxford is a city in the English county of Oxfordshire. It is also known as the "city of dreaming spires", a term coined by the poet Matthew Arnold to describe the dramatic architecture of the city. This is especially relevant to Northern Lights, where the traditional architecture of the city adds so much to the tone of the novel and helps invoke an otherworldly feel.
Lyra lives at Jordan College which, although fictional, seems to be based on Pullman's own Exeter college. Many of the other colleges mentioned in the novel are real, such as St. Hugh's, where several of Lyra's friendly rivals hail from. The architecture of the university is grandiose and spectacular, yet traditional. Our adventurous heroine roams all over the city, including onto the Library roof where, she confesses to her uncle, she and Roger often play.
Another feature of Oxford that is integral to the plot of Northern Lights is the network of rivers. These provide a highway for the riverboat-dwelling Gyptians, who will become valuable allies to Lyra as the story progresses. The main two rivers running through Oxford are the River Thames (called the Isis where it passes through the town) and the River Cherwell. In the book, canals are also used by the Gyptians in their narrow boats.
While Lyra is in the care of the Gyptians, they travel to the Fens in East Anglia, which in the world of Northern Lights appears to be the Gyptian's land.
The Fens are largely marshland, partly drained by canals which lead to the North Sea. From there, the Gyptians have easy access to Holland; the Gyptian language is thick with Dutch words.
The Fens are the location for the "Roping" - the gathering together of all the Gyptian families to discuss matters of importance.
The broadly used but vague "North" of Lyra's world seems to encompass various parts of our own world, including Lapland, Siberia and Norway.
When Lyra and the Gyptians first land in the North, it is at the fictional town of Trollesund, described in the book as the main port in Lapland.
It is likely that Trollesund is based on the port of Tromsø in our world, as they are both in the same general area (close to Svalbard and north of Norway).
Lyra meets the witch's consul here, as well as Lee Scoresby and Iorek Byrnison.
Lake Enara is the birth place and home of Serafina Pekkala, the witch who befriends Lyra.
Enara is the Swedish name for the real life Lake Inari in Finland. It lies in the northern part of Lapland, north of the Artic circle.
Lake Inari is one of the many real life places featured in Northern Lights that offer incredible views of the Aurora -- the Northern lights themselves.
In the world of Northern Lights, Svalbard is the home of the panserbørne, the armoured bears. In reality, Svalbard is a group of islands that constitute the northernmost part of Norway. They lie about halfway between mainland Norway and the North Pole.
The panserbørne are based on polar bears. The polar bear is the symbol of Svalbard, and they are one of the islands' biggest tourist attractions.
Svalbard consists of permafrost and tundra, where the soil is at or below freezing temperature, restricting the growth of vegetation. Much of the land is a treeless wasteland, a suitably bleak setting for the heart-wrenching climax of the novel.