In 1875, when the Clare county surveyor John Hill was designing the new road from Ennistymon to Lisdoonvarna, he had to find a way of bridging the River Aille where it flows through a narrow steep-sided gorge that is eighty feet deep in places. An ordinary single-span bridge that deep would contain so much stone it would probably be too heavy for its structure.

Hill's solution was ingenious: a light-weight, two-tiered structure with an ordinary semi-circular arch below, and above this a circular tunnel on top of which lies the road. This 120-year-old delight, known as the "spectacle bridge" for its appearance from the river, is still used on the main road today, a fine example of the ingenious work of civil engineers in Ireland over many centuries.

Ingenious . . . I use the word deliberately, for I recently learned that it and "engineer" share the same Latin root: ingenium, "a clever thing". And this new field guide to Ireland's civil engineering heritage is a celebration of many clever things.

Compiled with an eye to detail by two civil engineers - Ron Cox in Dublin and Michael Gould in Belfast - it also reveals the fundamental social importance of civil engineering, which makes transport both possible and safe, brings power and water supplies to our homes and industry, and takes the waste away. Where would we be without our roads, bridges, canals, railways, viaducts, lighthouses, reservoirs, power stations and quays, to list just some of the two hundred or so structures featured in this guide?

They include ancient buildings (like Newgrange, and the oakwood bog roads or toghers), medieval features (the beautiful pedestrian "clapper" bridge across a ford near Louisburgh in Co Mayo), as well as the recent (Ardnacrusha power station) and the thoroughly modern (the tunnel under the Lee in Cork).

As befits a field guide, the entries are arranged geographically. Each one includes a map reference, short description, construction details, names of contractors and designers, and references. Most are illustrated with a black and white photograph or a diagram. Comprehensive indices to people, places and topics are at the back.

There are fascinating insights into why things are the way they are (to cope with future floods, for example) and how they were built. Dublin's Liffey (or Metal or Halfpenny) Bridge, for example, the earliest known iron bridge in Ireland, was cast in sections in a Shropshire foundry, floated down the Severn to Bristol and thence to Dublin where it was erected in 1816.

The short historical notes also reveal the many short-sighted decisions that gave the kiss of death to a canal or railway, usually in favour of a road. Thus, old swing and lifting-bridges were often replaced by fixed, low-slung bridges that closed the navigation.

And the original route of the Galway-Clifden railway along the populated coast was overruled by the commission on public works in favour of the inland route which, not surprisingly, was never commercially successful. Who can say what Connemara would be like today if the original route had been used?

If I have one suggestion, it is that the authors might consider a more popular version of some of this material, since this book has been written and designed primarily for fellow engineers, and yet this facet of our heritage and environment, so much taken for granted, deserves a wider audience.

Mary Mulvihill edits Technology Ireland magazine; her guide to Ireland's scientific and technical heritage will be published later this year