If you thought the streets of Calcutta weren’t scary enough, here comes a house of horrors.

Pleasure in the form of petrification comes to town on Poila Baisakh, complete with a giant, hissing Anaconda.

But Calcuttans on Friday did not need any props to feel scared — it came free. A succession of rallies, political and apolitical, made it a day not for the weakhearted.

Unending streams of people and vehicles snaked through the streets like a giant Anaconda, as traffic slowed to a crawl for hours.

“It took me an hour to travel a kilometre in the afternoon while bringing my kids from school. It was scary,” said Dola Banerjee, 38, a resident of Lake Gardens.

But Dola’s kids — Pritam, 10, and Piyali, 6 — could soon lead her to a place selling fear for a fee.

The dread den — the brainchild of T. Srinivas, of house-of-horrors theme destinations fame — is coming up at Mani Square, on the Bypass.

For an entry fee of Rs 40, kids can shake hands with King Kong, feel the tremors of a 7.5-Richter quake, get chased by a flying cot, be ambushed by an apparition leaping off a windowsill or surrender to the serpentine Anaconda.

“Nothing thrills children more than a hearty scare, and even adults love to be entertained in dread dens crafted with imagination,” Srinivas, 38, told Metro.

The theme park — 6,000 sq ft — is being set up by Hyderabad-based Crazy Concepts & Mazes Pvt Ltd, through which Srinivas holds the copyright to his Scary House concept.

The Scary House theme was first introduced in Prasad Multiplex, Hyderabad, in 2004. Now, there are 12 Scary Houses across India.

The Calcutta project, which calls for an investment of Rs 30 lakh, will be the first to incorporate three formats — Scary House, Museum 15 AD and Mirror Maze.

The Scary House theme is that of an old haunted house that opens the door to a world of the dead and alien creatures, which come alive from behind creaking doors and moving walls.

Museum 15 AD is a 2,000-sq-ft dark room where visitors can meet puppet celebrities like Sly Stallone and Bill Gates. “For Calcutta, we will have Tagore, Mother Teresa and Netaji Subhas Bose as well in the animatronics section,” says Srinivas.

The Mirror Maze is a terror trap of a web of mirrors, quite like the climactic sequence of Enter The Dragon, greeting visitors with illusions of drowning in an ocean, being swept away by an avalanche or rocked by an earthquake.

Those stranded on the streets on Friday the 14th, of course, were drowned in an ocean of traffic and rocked by a storm of rallies.