Relocating council staff to Teesside's tallest building would cost as much as £50m, officials have revealed.
Middlesbrough mayor Andy Preston unveiled plans in December to move 650 staff to Centre North East, from the "crumbling" civic centre.
But leaders have shelved the move in the wake of the sky-high costs and coronavirus changing how people work.
A greener building is being sought out as a potential alternative, which could last 100 to 200 years, the mayor added.
Mr Preston told an executive meeting on Tuesday that the current civic building was expensive to run, with staff working in "pretty poor conditions".
'Staff need certainty'
The meeting heard a move to a new-look Centre North East was still possible but only financially viable if other tenants were found.
The independent elected mayor said the 19-storey tower was "three to four times the size" of what the council needed, with uncertainty about the Covid-hit office market creating more doubt.
"Moving into Centre North East would be a huge financial risk," he added.
"It would give us a building that wasn't particularly eco-friendly and one that would probably only have 40 to 50 years of its life left."
The council's current office building, which is attached to the town hall, is set to be demolished.
Most council staff have been working from home since the pandemic.
A £150,000 piece of work to assess different office options has been drawn up, with the preferred choice due to be unveiled in January. the Local Democracy Reporting Service said.
Labour group leader Matt Storey said the existing civic centre wasn't fit for purpose and staff "needed certainty".
"They've been phenomenal during Covid in getting us through the crisis," he added.
Mr Preston said the council would seek "sensible, sound advice" on its next steps.