The young men are on the roof of a solicitors office in Wrexham.
The firm says they have had to close their office due to the 'stand off', which otherwise has no connection to them.
It says the men have been there since midday on Wednesday, it is liaising with police, and hopes the situation is resolved as soon as possible.
A man who works locally has told ITV News there are a lot of police present in the area, trying to negotiate with the young men, who are throwing objects from the roof.
More top news
Improvements include new visitor centres, medieval chapel restoration and new interactive displays.
Arriva Trains Wales is set to double capacity on some of the busiest routes into Cardiff, it's been announced.
First Minister Carwyn Jones is in north Wales today to open a new hangar at Hawarden Airport.