Kolkata: KMC on Thursday demolished a stall illegally constructed on the ground floor of the Indian Coffee House building on College Street. KMC will conduct a drive against three more illegal stalls that were locked on Thursday.Civil officials said space for the stalls was carved out of the century-old building's thick, load-bearing walls, hollowed out in sections.The stalls also encroached on the pavement. A month ago, Coffee House regulars spotted the wall being demolished and alerted cops, who stopped the work. A complaint was filed with KMC, which issued a stop-work notice and filed a police complaint. The building on 15, Bankim Chatterjee Street has a Grade I heritage tag as the Indian Coffee House is located there. The Graded List mentions that "no external change will be permissible" in a Grade I structure. According to locals, after Chuckervertty, Chatterjee and Co Ltd, a shop on the ground floor facing College Street, vacated the premises, the new owner began scooping out the thick walls to create space for small stalls.A civic official said the new owners did not seek KMC's permission for the work. "Any work in a Grade I heritage building requires permission from the KMC heritage conservation committee. Not only was this not sought, but the stalls that were constructed were also illegal," the official said.