Churches in Ireland have had a rough time over the years. Thanks to centuries of conflict, many were defaced or destroyed. And yet those that survived – even the ruins – are repositories of all kinds of histories, mysteries and truly strange tales.

Care to find out more?

St Michan’s Church in Dublin is surely one of the creepiest – “unique and, let it be noted, macabre,” says the guidebook Frommer's – and is believed to have inspired Bram Stoker, the Dublin-born author of Dracula.

The church itself is interesting in its own right – housing the organ Handel played as he was composing The Messiah, and Irish nationalist martyrs buried in the graveyard – but it’s the crypt and its mummified inhabitants that really take your breath away…

No one quite knows the processes by which the bodies have been preserved. Some theories suggest the limestone of the walls dried the bodies; others that the methane of the soggy ground did the job.

But whatever it is, arms and legs stick out of coffins, and bodies whose identities are long lost lie exposed in their coffins.

If it’s ghosts you’re after, try St Columb’s Cathedral, Derry~Londonderry for size. It’s said to be haunted by William Higgins, a former bishop, ever since his grave was disturbed in 1867. People working there have heard footsteps crossing a locked gallery; then there was the strange matter of the organ. The original had been vandalised and an electric replacement installed, but it started to emit a noise even before the power had been switched on...

Secrets are concealed in churches across the island, some of them so strange that they remain unsolved. The Collegiate Church of St Nicholas in County Galway is rumoured to incorporate part of a chapel owned by the Knights Templar, the shadowy order of warrior monks founded in 1118 to protect pilgrims to the Holy Land.

Certainly there is a strangely carved pillar, the Apprentice Pillar, unlike anything else in the church, whose unusual decoration echoes one in Scotland’s Rosslyn Chapel, which featured in The Da Vinci Code.

A grisly reminder of more savage times can be found in St Peter’s Church in Drogheda, where the head of St Oliver Plunkett, a former archbishop of Armagh, is preserved in a shrine. Armagh, which is just up the road, ­was named the heart of Christianity in Ireland by St Patrick.

For those of you looking to find out how part of St Oliver Plunkett’s anatomy came to be in the church, he was hanged, drawn and quartered by the English in 1681, but his head was eventually brought to Drogheda. The church also has his forearms; and the door of his cell is at Newgate Prison.

The mysteries continue to this day. “In what seems like a surreal subplot from a Dan Brown novel,” reported The New York Times, “a number of religious relics have disappeared from churches across the country.”

Fragments of the True Cross were stolen from Holycross Abbey in Tipperary; in Dublin the reliquary that held the jawbone of St Brigid, and the 12th century heart of St Laurence O’Toole in Christ Church Cathedral, were crow-barred out of their casings.

The relics from Holy Cross were recovered, but the other two have vanished into thin air. Why?

Perhaps that’s just another puzzle we shall never solve…