From Wales, land of place names that are hard to pronounce and even more difficult to spell, comes Britain's longest (1,007 feet long) and highest (126 feet high) aqueduct — technically, a navigable water bridge that dates all the way back to 1805 when civil engineer Thomas Telford completed a magical cast-iron "stream in the sky" supported by 18 hollow mortar pillars made from lime, water and ox blood. Yes, ox blood.
Carrying the Llangollen Canal across the River Dee near the Welsh/English border, it costs a mere $10 to embark on a dizzying 45-minute voyage across back and forth the historic span — a UNESCO World Heritage Site, by the way — via a 50-person narrowboat named Eirlys ("Snowdrop"). Or you can walk along the towpath. While a singular experience (aside from castle-hopping and attending male choral concerts, what else are you busy doing to in rural northeast Wales?) serious acrophobics may want to sit this one out. It's worth noting that Pontcysyllte ("Bridge that connects") isn’t the only navigable aqueduct along the Llangollen: Just a few miles downstream in the Ceiriog Valley, you'll find the daintier but easier-on-the-tongue Chirk Aqueduct, also designed by late 18th century infrastructure wizard, Thomas Telford.