The Khmer built amazing temples and cities, but to travel between them they built an advanced infrastructure of roads and bridges that bears comparison with that of the Roman Empire. Many of these ancient routes are still used today.
Travellers on Route 6 from Siem Reap to Phnom Penh can see many pre-Angkorian bridges alongside the road. Almost every bend on the road from Damdek to Kampong Kdei is a diversion around these ancient bridges. Many are little more than large culverts, but there are several larger structures, including the magnificent Spean Praptos at Kampong Kdei.
Spean Praptos is truly spectacular, with 22 laterite arches. Spanning the Chikreng stream at 75 metres, it is the largest corbelled stone arch bridge in the world. It has a classic balustrade with nine-headed hooded Nagas at each end. The Nagas at the south end are the best.
Spean Praptos used to take the traffic on Route 6 until 2005, when Route 6 was improved. The original intention was to reinforce the bridge with concrete, but the alternative bypass was considered to be of more benefit for the villagers, and this left the structure intact.
Travellers can catch a glimpse of Spean Praptos while crossing the new concrete bridge, but for a much better view, drive 100 metres down the old road. It's worth asking taxis to take a short detour to catch this sight.