As an Irish  Foreign Affairs delegation meets with senior Iranian leaders, European Correspondent Paul Cunningham reports from Tehran on some initial impressions in Tehran.

Day one of my first visit to Iran and we start big - the Mausoleum of the Grand Ayatollah Ruhollah Khomeini, leader of the 1979 revolution which ended the reign of the Shah and ushered in an Islamic Republic.

Sited south of Tehran, not far from the Khomeini International Airport, we'd caught a glimpse of the huge shrine the previous night as cameraman Pol Reygaerts  and I were en route  from the airport to downtown Tehran. 

But it's only during daylight that the full scale of this enormous structure becomes apparent.

The shrine was built close to the graveyard which holds many of the 'martyrs' from the Iran-Iraq war of the 1980s, during which an estimated that half a million Iranians were killed. 

The complex is still under construction and when finished will house a cultural and tourist centre, a university, a seminary, shopping malls, and gardens spread over 5,000 acres. 

Khomeini died back in 1989. It was reported that more than two million people took to the streets to mark his funeral of the revered political and spiritual leader. So why, nearly 25 years later, is his mausoleum still unfinished?

One visitor told me his belief was that the project continues to expand as the complex becomes an ever bigger place of pilgrimmage.

Non-Muslims are allowed to enter the shrine. We handed in our shoes and slowly padded across the ornate Persian carpets. The atmosphere was friendly and courteous. We were  greeted with smiles and 'hellos' from both the Revolutionary Guards on security watch and the pilgrims. We arrived early in the morning, so many pilgrims had yet to arrive from Friday  morning prayers.

Small birds swooped overhead as we entered the inner chamber. Khomeini's remains lie in a sarcophagus under the main dome. On the back wall hangs a huge poster of the deceased  leader, his eyes watching you watching him, framed by that recognisable black turban and white beard.

Beside it, another poster - his successor Ali Khamenei, Iran's current Supreme Leader.

On either side, hang posters of Khomeini's two sons: Mustafa who died in Iraq in the 1970s, and Ahmed who died in the 1990s.

I stood and wondered: what relevance does Khomeini have in today's Iran? Will the new President  Hassan Rouhani herald a new era for Iran?  Are the calls for 'death to America going to fade? Will the nuclear talks in Geneva result in a new and more harmonious relationship with the West?  Or will the current hopes simply fizzle out?

It was time to leave the Khomeini shrine and try to find out.