A footpath through one of Newport's most historic monuments has been closed to the public, because of street crime and persistent vandalism.
Crime levels have increased in the area around the castle
Reports of assaults, street robberies and anti-social behaviour around the city's castle have risen in recent months.
Police said they have dealt with hundreds of complaints of unlawful activity there since 2004.
Newport Council said it was "disappointed" to close the path.
The 14th Century ruin, which is close to the city centre, stands on the banks of the River Usk and is regularly used by pedestrians.
But police advised the council that shutting the path would be an effective way of combating the amount of crime which is taking place in the area.
Following their advice, a public consultation was carried out which has resulted in a decision to close the footpath.
A spokesman from the council said: "Newport city council has a duty to ensure that the castle is protected from vandalism and to ensure the safety of the public.
"It is disappointing that this action is needed however we must ensure the preservation of the castle and reduce the opportunities for criminal and anti-social behaviour," he added.
Work is underway to close the path with people being advised to use the overhead walkway
Cadw, the historic monuments agency, is now being consulted over the proposals and there are plans for new information boards, guided tours and floodlighting to enhance the castle's appearance.