For five days, the city stops being a city.

The armature goes up first: bamboo for the frame, then rice straw bound with jute rope into the rough mass of a body. It looks like a scarecrow with too many arms, and it is built fast by people whose names you will not read anywhere.

Then the clay, in two grades. Entel mati, a heavy clay from the riverbed, is packed on first. Bele mati, finer and mixed with rice husk, goes over it for the surface. Between the two coats the figure is left to dry, and in a wet September that is what goes wrong.

Tradition requires punya mati, a handful of earth from outside a brothel in Sonagachi, on the argument that a man leaves his virtue at that threshold and the soil there holds it. Sex workers' collectives have pointed out, at length, that a city willing to build its goddess from their doorstep is less willing to let their children into its schools. The custom continues; so does the argument.

A mid-sized idol takes four to six weeks and sells for between forty thousand and two lakh rupees. Almost all of the year's income arrives in a two-month window, and the workshops carry the other ten months on credit.

Puja food is street food at a scale the street does not normally attempt. Rolls, chow, phuchka, biryani, moglai paratha, ice cream and fish fry, sold from stalls that appear beside every major pandal and vanish a week later.

Navami, the ninth day, is traditionally the biggest meal of the year. Every restaurant in the city is full, every household that is cooking is cooking mutton, and bookings for the good Bengali places go weeks in advance.

Bhog is the other half of it. Many community Pujas serve khichuri, labra, beguni and chutney on a leaf plate to anyone who queues, free, on Ashtami and Navami. It is often better than anything you will pay for.

Dashami ends with mishti: sandesh and rosogolla handed round after sindoor khela, whether or not anyone wants more sugar.

From Shashthi the city inverts. Nothing much happens before four in the afternoon and everything happens between nine at night and four in the morning. Roads close, the metro runs extended hours, and pandal-hopping becomes the only activity.

The queues are the experience. The big south Kolkata pandals can take two hours to enter, in a barricaded line that moves at walking pace, and the line itself becomes sociable.

Photographers work the crowd rather than the idols. The best night photography in India happens in these four nights, on ordinary streets, under lighting rigs built by Chandannagar technicians.

Maddox Square in Ballygunge is the exception that proves the rule: the pandal is unremarkable and the field around it becomes an all-night open-air social event where most of south Kolkata under thirty meets everyone they went to school with.

Bisarjan begins in the afternoon and runs deep into the night. Lorries queue along Strand Road; cranes lift the larger figures; the dhaak comes with them. Babughat and Bagbazar Ghat take the largest share.

The environmental rules have tightened. Water-based, lead-free colours are required, and the bamboo and straw frames must be pulled out of the water after immersion rather than left. Compliance is uneven and improving.

Two days later, the prize-winning pujas parade their idols down Red Road in a carnival before their own immersion. It is ticketed and is the only orderly event of the week.

The Kumartuli lanes are silent in November. By January somebody is binding straw again, for a festival eight months away.