A fire which destroyed an Orange hall at Lavin in north Antrim is being treated as arson, the police have said.
An Orangeman at the remains of the Orange hall
Paint was also splashed over the building. Firefighters were called to the blaze at the hall, four miles south of Armoy, early on Wednesday.
Sinn Fein and SDLP assembly members have condemned the attack.
An Orange hall in Claudy, County Londonderry, was also damaged. A number of flags were removed and paint splashed over the doors and windows.
Group Commander Charlie McCauley of the Fire and Rescue Service said the Lavin fire was a difficult operation for the firefighters.
"The building is severely damaged, two thirds of the roof had collapsed," Mr McCauley said.
County Antrim grand master Robert McIlroy said it was a blow for the community which had "rallied around their hall".
"The hall was used very much for the community. The doors were open and I feel it has done a great deal of damage to the community," Mr McIlroy said.
However, he said he believed people would show the "faith" and "resolve to get the hall rebuilt".
SDLP North Antrim assembly member Sean Farren condemned the attack and said it was exactly what was not needed ahead of a small Orange march in nearby Dunloy.
Sinn Fein's Philip McGuigan also spoke out against the attack.
"Attacks on people because of their religion or attacks on property because of their religion are wrong and should stop."
Meanwhile, police and politicians have condemned the people who placed a flag bearing an obscene reference to a teenage murder victim on top of a bonfire in Ahoghill, in County Antrim.
Michael McIlveen, a 15-year-old Catholic, was beaten to death in nearby Ballymena in May.
Flag made an obscene reference to Michael McIlveen
Ballymena SDLP Councillor Declan O'Loan said it was "truly shocking", while Sinn Fein's Philip McGuigan said the flag was a "disgrace".
County Antrim Orange Order Grand Master Robert McIlroy said there was no place for such "sectarianism or bigotry."
A police spokesman described the flag as a "disgraceful display" and said officers had liaised with community representatives to try to have it taken down.
During the eleventh night, the Fire and Rescue Service said more than 300 emergency calls were received in the hour after midnight on the eleventh night.
Between 2300 BST and 0100 BST, a fire appliance was sent to an incident every 41 seconds on average as bonfires were lit across Northern Ireland.
The bonfires are traditionally lit on the eve of 12 July parades which commemorate Protestant Prince William of Orange's 1690 Battle of the Boyne victory over Catholic King James II.
In south Belfast, fire crews led four people to safety after a blaze broke out in the roof space of a house in Donegall Pass.