I suppose we just cannot keep everything but some destruction seems worser than others. A timber circle was destroyed in the Kilmartin Valley in the late 1990's.

From British Archaeology no 29 November 1997
"The remains of a large prehistoric timber circle have been found in a commanding position at the head of the Kilmartin Valley in Argyll, home to one of the richest concentrations of prehistoric ritual monuments in Scotland.The timber circle was set high up on a terrace on the valley side, directly in line with Kilmartin's celebrated linear cemetery of Bronze Age cairns. The circle seems to have been approached out of the valley along a timber avenue reminiscent of the Avenue at Stonehenge and within and near the circle are several cist burials, including one with a complete skeleton preserved inside.
The circle, some 46m across, is assumed to be Neolithic in origin but to have been used throughout the Bronze Age. According to the excavator, John Terry of Scotia Archaeology, it may have been one of the principal ritual centres in the valley which contains numerous standing stone settings, a stone circle, elaborate rock art carvings, cairns and other prehistoric features. The circle is littered with post-holes, pits, and multiple post-alignments, he said, but they cannot all yet be fully explained.
The site lies within a sand-and-gravel quarry, and will be destroyed as quarrying goes ahead. The quarry itself has been the subject of controversy. It has been worked for several years, but in the late 1980s the quarry operators, M&K MacLeod of Lochgilphead, applied for permission for a major extension.
Both Historic Scotland and Strathclyde's regional archaeologist, Carol Swanson, advised against the development, because of the cultural sensitivity of the area. The regional council overruled their objections, because of the jobs the quarry would create.
Permission was granted before government planning guidance integrated archaeological protection into the planning system. The quarry operators were not required to finance an archaeological evaluation before their application went through in order to assess what survived under the surface and the site has subsequently proved richer than was expected.
As a result, according to Dr Swanson, the money the operators originally agreed to pay towards the dig is now likely to run out when the excavation is still only two-thirds complete."

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A bit sad that as late as the late 1990's an area as incredible as Kilmartin should be treated like this.