The world has its Seven Wonders, but Ireland also has a few historic marvels of its own, writes Mary Mulvihill.
Blame the ancient Greeks. They started this list lark in the 2nd century BC, when they compiled the Seven Wonders of the World: the pyramids of Egypt, the Hanging Gardens of Babylon, the Colossus of Rhodes, the Pharos of Alexandria; the Temple of Artemis at Ephesus, the statue of Zeus at Olympia and the Mausoleum at Halicarnassus.
Since then, people have been finding seven wonders everywhere: in the architecture of the Middle Ages, in the natural world and in the world of engineering, not to mention in the modern world - take your pick from the Great Wall of China, Leaning Tower of Pisa, Taj Mahal, Sydney Opera House, Eiffel Tower . . .
Time, surely, to suggest a shortlist of Irish wonders. And, yes, this is an unconventional seven, mixing the natural and the man-made. Lists are invidious, of course, and, sadly, seven is a small number. No room here for the prehistoric landscape at Céide Fields, for example, nor west Cork's enigmatic Lough Hyne. But perhaps they're on your shortlist.
1 The oldest fossil footprints in northern hemisphere, at Valentia Island, Co Kerry
The Irish word for fossil is iontaise. It's an appropriate term, for fossils are wondrous things, as you'll appreciate if you come to Valentia. A quirky mix of chance and chemistry has taken muddy footprints, turned them to stone and kept them safe for 385 million years. The oldest footprints (well, paw-prints) in the northern hemisphere, they are preserved in rocks by the cliff near Valentia radio station.
The prints were made by an early amphibian as it walked along a mudflat at low tide. They are fist-sized, suggesting the animal was about a metre long. The meandering track, discovered in 1992, is now protected by legislation, in recognition of its international importance.
Public access will be ready this summer; Valentia heritage centre, at Knightstown, has a plaster cast of the track.
2 The world's oldest astronomical observatory, at Newgrange.
Had the ancient Greeks known about Newgrange, they would surely have listed it as a wonder of the ancient world. For the elaborate burial mound, built 500 years before the pyramids and 1,000 years before Stonehenge, is arguably the world's oldest astronomical observatory.
Newgrange was designed so that, each winter solstice, the rising sun shines directly into the inner chamber and illuminates the interior. This precision engineering allows the turning point of the solar year to be marked. And it was built by people with neither metal tools nor the wheel. Access is via the Brú na Boinne visitor centre.
3 Giant's Causeway and the Antrim coast road, Northern Ireland
The Causeway Coast is famous for its basalt columns and Carrick-a-Rede's vertiginous rope bridge, but it also boasts numerous ancient volcanoes, eye-catching rock formations and dozens of rare minerals. No wonder UNESCO designated it a world heritage site.
The causeway's polygonal columns are so perfect that people once thought they must be man-made. In fact, they formed when a lake of molten lava cooled slowly, some 60 million years ago. Volcanic eruptions were rocking this corner of Ireland then, as North America and Greenland pulled away from Europe to create the north Atlantic Ocean; the hills of Knocklayd, Slemish and Carrick-a-Rede are the remains of some of those volcanoes. The spectacular coastline is made all the more dramatic by the contrast between the black basalt above and the white chalk beneath.
The ideal approach route is along the breathtaking Antrim coast road, from Larne to Ballycastle. Built in the 1830s to access the Antrim glens, it is a feat of engineering and a geological tour de force, hugging the chalk and basalt sea cliffs, passing amazing Jurassic fossil beds and going through an ancient sea cave.
4 The great telescope at Birr Castle, Co Offaly
In 1845, William Parsons, third earl of Rosse, built the world's largest telescope in the grounds of Birr Castle. The Hubble Space Telescope of its day, it enabled Parsons to see further into space than ever before.
Birr's great moment came in April 1845, when Parsons discovered the Whirlpool Nebula, and showed that this fuzzy object was actually a spiral cluster of stars, ending years of debate. His telescope's metal mirror, the largest ever made, measured six feet across (the next biggest was only four feet wide); the tube was an enormous barrel, 54 feet long. Massive walls and a complex pulley-and-chain system supported and sheltered the telescope, observing platforms and lifting mechanisms. And all done with local labour.
Although it remained the world's largest telescope until 1917, its bulk and boggy location quickly went against it. But Birr's Leviathan, as it is called, is now restored to full working order and open for viewing.
5 The botanical diversity in the Burren, Co Clare
This relatively small area of northwest Clare is disproportionately blessed with riches: a strange rocky limestone landscape, tremendous ecological diversity, amazing caves, several rare and vulnerable habitats, such as turloughs and seasonal lakes, and a rich plant life that is justly world famous. For the Burren is a botanical melting pot: arctic and alpine plants, normally found only in tundra regions or high mountain pastures, grow there, and at sea level, and alongside Mediterranean species. Nowhere else is there such an intriguing combination. In all, more than 600 plant species have been recorded, including 16 species of orchid. The flowers are at their best in late May. Please don't pick them.
6 The Boyne Viaduct, Drogheda,Co Louth
When the Boyne viaduct opened, in 1855, it was considered a wonder of the engineering world. The elegant bridge, the final link in the Dublin-Belfast railway line, spanned the Boyne's steep-sided estuary at Drogheda.
To minimise the structure's weight, the engineering team opted for a relatively new technique: a latticework construction made from wrought-iron girders. They calculated the stresses for each component and greatly increased engineers' understanding of wrought-iron construction. When completed, their bridge was the longest of its kind in the world, at 155 metres (adding the masonry approaches on either side brings the full length to 540 metres).
In 1932, the historic wrought-iron lattice was replaced by a steel-girder version, partly to accommodate a new, heavier generation of trains. The original masonry piers were retained, however, and the bridge is still in use. Watch for it next time you take the Dublin-Belfast train.
7 The Book of Kells, Trinity College, Dublin
This gloriously-illuminated manuscript is arguably the world's most famous book, and it's hard to think of any other volume that attracts as many tourists and academics. It was probably written by monks on the Scottish island of Iona in about 800 and brought to Kells Abbey, in Co Meath, to save it from Viking raiders. Since the 17th century it has been in Trinity's safekeeping. The book's 680 pages contain the four Gospels and related passages. The Latin text, written on calf vellum, is accompanied by intricate decorations; much of the detail can be appreciated only with a magnifying glass, although the work was done centuries before magnifying glasses were invented.
The book would have been costly to produce then, in terms of monk hours, vellum and expensive imported pigments, and of course today it is priceless. Yet, thanks to digital technology, you can now buy a copy on CD.
All seven Irish wonders feature in Mary Mulvihill's new book, Ingenious Ireland: A County-By-County Exploration Of Irish Mysteries And Marvels, published by TownHouse
Would you choose other Irish wonders? E-mail suggestions to sevenwonders@irish-times.ie or post them to Seven Irish Wonders, Features Department, The Irish Times, 11-15 D'Olier Street, Dublin 2. A selection of contributions will be published