Up to 80,000 people have demonstrated in Ankara against government plans to reform Turkey's administration.
A bill being considered by parliament would decentralise the administration and allow local government greater freedom in the hiring of staff.
Opponents fear that this could lead to job cuts and politicisation of the civil service.
The Turkish capital has not seen a demonstration of this size since before the Iraq war.
The demonstrators braved Ankara's bitter cold and snow to show their opposition to the plan.
The demonstrators braved winter weather to make their views known
Turkey has a very centralised system of government. Few decisions, even of the most minor kind, escape the scrutiny of civil servants in Ankara.
The governing AKP party want to loosen the control of the capital over the far-flung provinces.
But marchers believe swingeing job cuts could follow, and there is a political concern as well.
The current government is led by a party with its roots in Islamic politics while the civil service is one of the guardians of Turkey's secular status.
Critics of the decentralisation plan believe that allowing local government greater flexibility over the hiring and firing of civil servants could open the civil service to religious influence.