
The seventh and eighth days of Durga Puja are two of the most auspicious days of the great Bengali festival. (You’ll notice a lot of ‘Maha’ in Hindu festivals. It’s a prefix meaning ‘great’.)
Maha Saptami
According to www.indiasite.com
The morning of maha saptami (seventh day) is taken up with the worship of the deity, followed by anjali when a devotee offers prayers and flowers on an empty stomach, amidst the chanting of mantras to the Goddess. Only then can one make a beeline for the prasad (sweetmeat offered to the deity).
The lunchtime meal is called Bhog. By evening, the streets pulse with the sounds of the dhaki drums and the pandals buzz with anticipation of Maha Ashtami.
Maha Ashtami
The eighth day of Durga Puja actually begins at 8:30 tonight. On this day the priest (purahi) offers prayers (aradhana) and breathes life into the idol of the goddess Durga’s.
During the Puja week, the entire state of West Bengal as well as in large societies of Bengalis everywhere, life comes to a complete standstill. In traffic circles, playgrounds, ponds, wherever space is available — elaborate structures called Pandals ‘are set up, many with nearly a year’s worth of planning behind them.
These pandals aren’t tents. They can be massive and ornate structures, and come in all varieties. Last year, a legal furor arose over one such pandal that bore an uncanny resemblance to Harry Potter’s Alma Mater, Hogwarts:

Harry Pandal?
Maha Ashtami is the most venerated day of the festival because it celebrates the victory of Durga over the demon Mahishasura. (See Durga Puja.)

Durga Puja - Bengal « Everyday’s a Holiday said,
October 6, 2008 at 8:40 am
[...] October 5/6: Maha Saptami [...]
Navami & Dashami « Everyday’s a Holiday said,
October 8, 2008 at 10:51 pm
[...] falls right after Maha-ashtami (eighth day) and opens with Sandhi Puja, the ritual that recalls Durga’s defeat over [...]