Celebrations have begun this week to mark the bicentenery of the spectacular Pontcysyllte Aqueduct in Wales. The aqueduct, near Wrexham, was drained and completely refurbished in 2003 in preparation for the celebrations. The events will culminate with a firework and re-enactment ceremony on 26 November, 200 years to the day when the aqueduct was first opened in 1805. The world-famous 307m-long iron trough aqueduct towers 38m over the Dee Valley. It was built by canal engineers Thomas Telford and William Jessop. The innovative use of an iron trough – sealed with Welsh flannel boiled in sugar and using an ox-blood mortar – allowed them to create what remains the highest navigable aqueduct in the world.