Rising some 60 feet high, the Interpretive Center won Ireland's Building of the Year Award when it opened in 1993. It is a handsome three-leveled edifice, the bottom third sided with bog turf, so that the building appears to have sprouted naturally from the ground. Gray-green limestone slabs, the same stone found in Ceide Cliffs, front the middle section. And the towering apex is composed of glass walls supported by stainless-steel beams. Designed by Mary McKenna at Ireland's Office of Public Works, these architectural elements are at once harmonious with the environment and in striking contrast to it.

The pyramid's loftlike, oak-and-sandstone interior is just as stylish. The main floor houses crisp exhibitions on the archaeology and botany of Ceide Fields; a sleek, 75-seat theater screening a short documentary on the region; and a pleasant cafe, serving soups, sandwiches and pastries. The statuesque centerpiece is a 15-foot section of copper-colored 4,500-year-old Scotch pine retrieved from a nearby bog. A second-story gallery contains exhibitions on local geology, while the glassed-in third floor consists entirely of a platform for viewing the fields, cliffs and ocean.

The center provides a much-needed window onto the landscape's often enigmatic patterns of ruins -- and a much-needed shelter from northwest Mayo's frequent rainstorms. But since an hourlong tour of the excavations was about to begin, I put off exploring it, eager to get outside into the sunlight that now streamed through the glass apex.

The tour guide, Dredagh O'Connor, a doctoral student at the University of Edinburgh and a native of Ballycastle, ushered our small group out the back entrance and up a wooden staircase ascending Ceide hill. Gravel pathways snaked through the grassy boglands, which, up close, reveal purple heathers and sprays of spotted yellow orchids. The tour follows one such pathway around the boundary of a five-acre field once inhabited by a Neolithic family. As she led us across olive green moors stretching south to the horizon, Ms. O'Connor explained the extent of what we were looking at.

Ceide Fields encompasses hundreds of individual, interlinked Stone Age farms once inhabited by as many as 1,000 people. These homesteads were surprisingly well organized. Sets of parallel field walls, over a mile long, run inland from the coast. Perpendicular dividing walls crisscross these longer walls into neat, rectangular plots of anywhere from 5 to 17 acres. Each plot provided just enough room to sustain an extended family of cattle herders and wheat farmers.

While some sandstone walls have been excavated, most remain buried in a secondary, subterranean landscape. To find these underground walls, archaeologists have borrowed the traditional method of local farmers to dig for trees buried beneath the bog: long iron probes are thrust into the bog; if they strike something hard, a whitewashed bamboo rod is inserted into the probe's hollow center and left as a marker indicating the existence of a wall or a tree.

Thus much of what visitors see at Ceide Fields are these bamboo poles delineating the ancient field wall system -- which somewhat resemble an enormous game of connect-the-dots. And the center and tour help connect these dots with intriguing evidence about prehistoric life.