Construction on Chirk Tunnel started in 1794 and was completed in 1802, immediately by Chirk Aqueduct, it is 421 metres long and has a towpath the full length inside. The tunnel is single boat width, so passing is not possible. Boaters are required to operate a headlight which warns other boats that you are in the tunnel.
At a length of 710 ft and 70 feet high, Chirk Aqueduct when completed was briefly the tallest navigable aqueduct in the world. As you pass over the River Ceiriog underneath, you pass over the England - Wales border. (Don't worry you don't need you passport here). It forms part of the Pontcysyllte Aqueduct World Heritage Site, later a railway viaduct was built alongside but made to be taller to emphasize the superiority of rail over boat.
Offa's Dyke was constructed in the 8th Century and roughly follows the border between England and Wales, then Mercia and Powys. It had a ditch on the Welsh side and the displaced soil was built into a bank on the Mercian side, suggesting it was built as a defensive barrier. Running from sea to sea, from the River Dee estuary in the north to the River Wye in the south, a total of approximately 150 miles.
George Borrow noted in his folklore classic Wild Wales that 'it was customary for the English to cut off the ears of every Welshman who was found to the east of the dyke, and for the Welsh to hang every Englishman whom they found to the west of it. A footpath was opened in 1971 and closely follows the dyke. Search Offa's Dyke Chirk, and you will be rewarded with a short stretch of history.
Chirk Castle was built by Roger Mortimer de Chirk, as part of King Edward I's chain of strongholds across the north of Wales. The castle was bought by Sir Thomas Myddelton in 1593 for £5,000, in today's money it would be in excess of £11 million, Sir Thomas was a founder of the East India Company and an investor in the expeditions of Drake, Raleigh and Hawkins.
Offa's Dyke runs through the park and can be seen from the air beneath the waters of the artificial lake, and is visible as a low bank as far as Home Farm, west of the castle. South of the castle it is better preserved, running to the west of the track, and out into the fields beyond, beside the footpath. Some very important people have been married here. The castle is now owned by the National Trust and is open to the public between March and October.