What goes up must come down – unless it’s a Palestinian flag at the top of Dublin’s tallest landmark that no one knows how to remove.

The flag appeared on the 120-metre Spire on O’Connell Street last September and for seven months it has defied every proposed measure to take it down. Who installed it and how remains a mystery.

City authorities have considered options such as climbing ropes, “bespoke ladders” and a 300-tonne crane and rejected them as too dangerous, expensive or futile.

“Someone could just come along again and drop another flag on the Spire,” an engineer told Dublin city council, according to internal correspondence reported in the Irish Times this week. “We have probably taken the options for accessing the Spire from the ground up as far as we can at this stage.”

A brisk wind on Wednesday fluttered the small, green, red and black of Palestine high above traffic and pedestrians. Media interviews suggest many people are oblivious to it, as it often gets tangled and is difficult to see, but approve once notified of its presence. Ireland is one of the EU’s most outspoken critics of Israeli action in Gaza and the West Bank.

The Ireland Palestine Solidarity Campaign welcomed the stunt. “This is some feat of acrobatics or ingenuity, or both! The streets are with Palestine!” it posted on X.

No individual or group has claimed responsibility but the flag is suspected to have been dropped by a drone. It is attached to a hoop and is about 105 metres up the Spire, a stainless steel structure that resembles a needle.

The site, opposite the General Post Office that was occupied during Ireland’s 1916 rebellion, is historic. A pillar of Adm Horatio Nelson, similar to that at London’s Trafalgar Square, occupied the spot until the IRA blew it up in 1966.

Authorities erected the Spire in 2003. Officially called the Monument of Light, it has been nicknamed the Stiffy by the Liffey and the Stiletto in the Ghetto.

The options considered by authorities, including the ropes and special ladders, have been deemed too risky by experts.

“They told us that they would only consider an option involving a mobile crane and a basket,” the engineer told the council, according to the Irish Times report. The disruption and cost of such a measure has deterred action.