Last night, the guard working at her rented accommodation in the city's Rohaniya area allegedly snatched her cellphone, beat her up and raped her. The man is absconding.
The police said the woman has undergone a medical check-up at the hospital where she has been admitted and a report is awaited. Doctors have said she is out of danger. A hunt is on for the guard, said senior police officer Nitin Tiwari.
"The accused has been identified and all legal formalities will be completed soonest. He is a chowkidaar (guard) of the place where she was living," Mr Tiwari said.
Varanasi, the constitution of Prime Minister Narendra Modi, also is the holiest city of the Hindus. One of the major shrines of Lord Shiva, it draws thousands of foreign visitors every year.
The BJP government led by Yogi Adityanath, which came to power in March and completed 100 days earlier this week, has said tackling crime against women is one of its priorities. According to government data, over the last 100 days, 16,152 complaints of crimes against women have been registered; 11922 people arrested and 1922 accused have surrendered.
Soon after coming to power, the state government had formed anti-Romeo squads, police teams specially formed to stop harassment and molestation of women in public places. It was a pre-election promise of the BJP, but the execution drew complaints of excess against the state police.