Space at Birmingham landmark Fort Dunlop - transformed by developer Urban Splash from a tyre warehouse into a state-of-the-art mixed-use complex - is being snapped up at the rate of 1,000 sq ft every day.
Since December last year lettings at the complex have totalled 277,000 sq ft.
Just 60,000 sq ft of space is now left - half of which is already under offer. And a major city centre business is expected to officially announce its move to the building in the next few weeks.
The success of Fort Dunlop is in sharp contrast to the latest Cushman & Wakefield UK Cities Monitor annual report, which suggested that Birmingham has slipped in its UK ranking for business locations to third behind Manchester and London.
Nathan Cornish, managing director of Urban Splash Midlands, said: "To reach our ambitious target for Fort Dunlop in just nine months has simply astonished us.
"We are just delighted that so many businesses have seen that the Fort is more than just another office building.
"Its history, its design led reinvention, its retail offer and of course its competitive rents have proved lethal in attracting a wide range of office tenants from different business sectors."
He added: "This result sends out a clear and positive message about Birmingham. When commercial space combines great design with value for money, the city is an obvious and popular option to choose to locate and do business in."
As part of the lettings already secured, two individual companies have each taken an entire floor of over 53,000 sq ft, representing some of the largest single floor plate transactions in the West Midlands in the last decade.
The latest to take space include ICT provider Service Birmingham; building and development group, Linford and B24 Gym.
Service Birmingham is one of the businesses taking an entire floor. It has signed up to all 53,477 sq ft of the fifth floor.
A joint venture between Birmingham City Council and IT firm Capita, Service Birmingham's move to Fort Dunlop will help the organisation's growth in the region.
Phil Braithwaite, chief executive of Service Birmingham, said: "This move provides us with the capability to meet our plans for growth in the region and is the next stage in our aspiration for a shared service centre for the public sector.
"As a design-led space, Fort Dunlop is the ideal choice for Service Birmingham to locate an innovation centre showcasing new and emerging technology. With this new facility, we will also be able to deliver and host training in our planned learning and development hub."
Emily Jones, commercial lettings manager for Urban Splash, added: "Unlike many business parks Fort Dunlop has been created to offer more than office space to the 2,000 plus future tenants."
Demand was showing no sign of slowing down, she added.