A SECOND World War siren echoed through Derry to signal the culmination of the city's biggest ever Halloweeen carnival on Monday night.
Thousands of people packed the city centre for the annual City of Bones carnival parade which was launched by mayor, Hilary McClintock resplendent in her own super hero outfit.
Every vantage point along the banks of the Foyle was also taken up as the four-day carnival came to a spectacular end with a huge fireworks display launched from barges on the river.
The carnival has led to Derry being named "best Halloween destination in the world" by American newspaper, USA Today.
To celebrate the 30th anniversary of the start of the annual carnival, organisers chose an "Out of this World" theme with aliens descending on the city last night.
Derry City and Strabane District Council's events officer, Sharon Meenan, said extra-terrestrials had transformed the city’s craft village into a craft planet throughout the weekend.
"We already have a global reputation as the official best Halloween destination in the world but our 30th anniversary celebrations are so big this year that they have attracted interest from around the solar system and beyond," the council spokeswoman said.
From early afternoon, the city's streets starting filling up with revellers in colourful and original costumes.
They were entertained by the "Return of the Saurus," huge dinosaur-like animals which stalked the city centre throughout the afternoon. A musical backdrop was provided by the drummers of the Spark! Street theatre show.
There was also a surprise visit on Monday night by the "ghost of Dopey Dick."
Dopey Dick was the name given to a killer whale which strayed into the River Foyle in 1977, entertaining crowds over a number of days before he returned to the sea.
Monday night's celebrations brought the curtain down on a weekend of Halloween events in Derry.
An estimated 40,000 people attended a range of events in the city centre and on Derry's walls.
These included fancy dress dances, a food and craft market, a 5km "Zombie" run and ghost tours of the most haunted sites in the city.
With almost every hotel bed sold out in the city, the mayor said it looked as if this year’s carnival would surpass the success of previous years.
"The world knows no-one throws a Hallowe'en party like us," Mrs McClintock said.
Meanwhile, crowds gathered in Dublin to mark Halloweeen, with the Bram Stoker festival coming to a close with a huge parade through the city centre.
The Dublin Fire Brigade said on Monday night that it had responded to more than 100 calls since midday.
