Mayanagar (transl. City Of Illusions), released internationally as Once Upon A Time In Calcutta is a 2021 Bengali-language drama film directed by Aditya Vikram Sengupta. It is the third film by the Indian director and produced by Wishberry Films, in association with For Films, with Catherine Dussart Productions (of France) and DUOfilm As (of Norway). The film had its world premiere at the 78th Venice International Film Festival in September 2021.

The film stars Sreelekha Mitra as the protagonist, along with Arindam Ghosh, Bratya Basu, Satrajit Sarkar, Anirban Chakrabarti, Rikita Nandini Shimu and debutant Shayak Roy in supporting roles. The film was in development since 2015 and was part of the LÁtleier Cinefondation at the Cannes Film Festival before it was supported by CNC, Sorfond and NFDC Film Bazaar.

Sengupta says he got the idea for the film when he took a picture of a dinosaur statue outside Kolkata's Science City, which was fast being overshadowed by the construction of a new flyover – a literal representation of a relic from the past, juxtaposed with a symbol of Kolkata's economic development. To Screen Daily, Sengupta mentions, "It looked like the flyover and the dinosaur were about to start a race". It received two awards at New York Indian Film Festival, 2022, including Best Direction for Sengupta and Best Actress for Mitra. The film was released theatrically in India on 7 February 2025.