"The stone bridge"
Two hundred metres east of Thommanon, just before crossing the river - which here has been diverted from its original course and whose bed has become more deeply cut since angkorian times - the road passes the remains of a sandstone bridge on the left, built no doubt at a later period if one is to judge by the number of blocks that have been re-used in the composition of its masonry.
The original foundation is now much higher than the level of the water even during times of flooding, indicating the extent to which the hydrology of the region has changed over the centuries since the abandonment of the ancient barrages.
The need to vault in successive corbels in the same manner as in the galleries of the monuments has forced the Khmer to be content with narrow arches between massive piers - which required the doubling of the width of the river as it passed under the bridge in order to obtain sufficient flow. The remains of 14 arches of 1m.10 in width are separated by piers of 1m.60.
The Spean Thma was cleared by H. Marchal in 1920.