There are few more prestigious addresses nor a more admired building in Dublin that the American embassy in Ballsbridge.
The Chancery Building, to give it its proper title, opened in May 1964 in the triangle of land bounded by Elgin Road and Pembroke Road. Both the Taoiseach Seán Lemass and President Éamon de Valera were in attendance.
On its first day alone 5,000 came to admire this futuristic construction which has worn its years well unlike many of the monstrosities built in 1960s Dublin. Its circular shape, designed by Harvard professor John M. Johansen and Irish architect Michael Scott, was an homage to ancient Celtic monuments, most notably Newgrange, to roundstone forts and Martello towers.
Its design also invoked the original stars and stripes flag with its 13 stars representing 13 states enjoined in a circular motive.
When the embassy opened, America's principal enemy, the Soviet Union, was engaged in an overt arms race with nuclear weapons and a huge army. Embassies were not regarded as targets though, in a nod to the nuclear age and the Cold War, two floors of its five floor construction is underground.
Now America's enemy use covert means and the building is one of the best fortified in Ireland. Where once there was open access from the street, the embassy now is shielded by high, blastproof walls and security cameras.
The only time the public gets to visit is usually for the life-changing process of obtaining a visa to live or work in the United States. It still has to be done in person and at the embassy.
On Friday the embassy will be part of Open House Dublin (OHD) for the first time and the public will be able to pre-register to visit.
Run by the Irish Architecture Foundation, Open House allows access for this weekend to the interior of some of the city's most prestigious buildings which are not usually open to the public.
The embassy has played host to three US presidents Richard Nixon, Bill Clinton and Barack Obama. A fourth, John F Kennedy, was a champion of the building which was initially condemned in Congress as resembling a "pile of flap-jacks with a pat of butter on top". It cost IR£750,000 (€14 million) and the pre-cast concrete blocks had to be shipped from the Netherlands on barges.
Sadly President Kennedy never lived to see the finished embassy in the land of his ancestors.
It is most famously associated with the incident in 2011 with President Obama when the presidential limo, nicknamed The Beast, got stuck on the security ramp exiting the embassy compound.
The interior of the embassy is dominated by the three-storey atrium called the Rotunda which reaches to the ceiling and resembles an opera house with balconies opening out on to the floor area where receptions and staff gatherings are held. Somewhat incongruously an old-style phonebox painted green in in the corner.
The building is well loved among staff but unfortunately has been outgrown by the needs of the embassy for more space.
The embassy has an option agreement to buy a site where the old Jury's Hotel is located across the street. "Sometime in the next 18 months we hope to be able to buy that land," said Christopher Wurst, the acting deputy chief of mission, who is running the embassy until the new ambassador Claire Cronin arrives either before the end of the year or early next year.
Mr Wurst stressed it could be many years before the embassy moves to a new location given the vagaries of design, planning permission and construction. “We will be here for a good while yet,” he said.
What will happen to the building when the embassy is vacated? “It’s a historic piece of architecture. It’s hard to imagine. That’s the billion dollar question that we don’t know the answer to,” he said.