WHAT's red, blue, purple and green and holds 1,500 people?
The new eircom headquarters.
And our pictures show Dublin's first red-light district in decades lighting up as engineers test the unusual lighting system which will illuminate the night sky around Heuston Station.
The system allows engineers to light up the building in multiple colours, but eircom chiefs are remaining tight-lipped as to what they plan to do with it.
At the moment, they're just testing, but when they decide what to use it for, they'll have to seek approval from Dublin City Council.
Depending on your point of view, it's the epitome of tackiness or state-of-the-art technology. But while new to Ireland, there are other examples of the technology used throughout the world.
The National Library of Belarus -- a rhombicuboctahedron, or diamond shape -- is lit at night using thousands of LED fixtures, while the Full Moon Tower, the centrepiece of Galaxy Park, the main civic plaza in Tianjin, China, also has the technology.
Eircom says that, despite all the lights, the building is environmentally friendly and is designed to ensure that heating bills don't cost the earth.
"The state-of-the-art facility has been designed to the highest standards of sustainability," a spokesman said. "The building incorporates a twin skin facade to maximise natural ventilation, to cool the building and minimise energy costs.
"The system is currently going through its initial testing phase. A decision on how to use the lighting system has yet to be taken. Staff have started to move in to the building and it is hoped to be fully occupied by late September."
The HQ, at 1 Heuston South Quarter, off St John's Road, will hold 1,500 staff.