Bruntwood has put City Tower in Manchester on the market, with an estimated price tag of £125m.
The Manchester-based office investor-developer has instructed CBRE to market the 30-storey tower after it attracted interest from international investors.
The tower, which is fully let, is the third tallest building in Manchester at 107 metres and totals 615,429 sq ft of office, retail, leisure and hotel space.
The sale would be the biggest office transaction in the region since Co-operative Group's headquarters in One Angel Square, Manchester, sold for £142m in February 2013. A sale of City Tower at the asking price would reflect a yield in the region of 7%.
Tenants include Indian outsourcing firm Aegis, recruitment specialist Hays, and Bruntwood also has its headquarters there.
Chris Oglesby, chief executive of Bruntwood, said: "There has never been greater domestic and international investor interest in Manchester property market than at the current time. The city's relentless, strategic focus on growth through the downturn means it offers a particularly strong investment proposition as the UK economy recovers and at c1m sq ft gross on a three acre site, City Tower is the iconic, landmark Manchester office building.
"It has recently been completely refurbished to a high specification and is fully let, so it is no surprise that we have had unsolicited approaches from a number of investors over recent months. We have therefore instructed CBRE to conduct a limited marketing campaign for us and are pleased that the building is helping attract international investors into the city."