The couple, which arrived in the city late Sunday, went from one temple to another to perform the rituals in the dead of night.
A local journalist, who sneaked into the heavily guarded Kashi Vishwanath Temple in the guise of a priest, witnessed the rituals that began at around 3 a.m. and continued till nearly 6 a.m. Two rituals were performed at the temple and one at the Sankat Mochan Hanuman temple nearby.
"The rudrabhishek puja performed by the duo in the presence of the entire Bachchan family is usually done by married couples only," said a temple priest who did not wish to be identified.
Family priest Chandramouli Upadhyaya, who was the first to call on the Bachchan family at the Taj Ganges hotel shortly after their arrival, told media persons: "The family was here to perform certain prayers on the birth anniversary of Amitabh's father, famous Hindi poet Harivansh Rai Bachchan."
However, when scribes sought to know what Aishwarya had to do with such a closed family affair, he said: "I don't know."
Bollywood's first family arrived here by a chartered flight around 10.20 p.m. and were huddled into waiting vehicles and driven straight to the Taj from the airport's rear gate to avoid inquisitive media persons and cameramen.
Upadhyaya visited them after they reached the hotel. Later, around 2.30 a.m., senior district officials escorted the family to Kashi Vishwanath Temple where priest Pandit Sitaram Shastri carried out a special 'mangala aarti' for them, which was followed by the 'rudrabhishek' puja.
Besides Amitabh, or Big B as he is popularly known, his actress-MP wife Jaya, daughter Shweta, brother Ajitabh and niece Namrata were amongst those who joined in the prayers. Samajwadi Party General Secretary Amar Singh, who had arrived with the entourage, was present as well.
Around 4.30 a.m., they left for the Sankat Mochan temple and attended a nearly hour-long aarti there.
They were surrounded by an extremely tight security ring comprising local police and personnel from the Sahara India group.
The entourage returned to the hotel around 6 a.m. While Abhishek and Aishwarya are scheduled to leave for Agra, Amitabh, Jaya and the others are to flying back to Mumbai, a local official said.