Up on the mountains, the weather is crap. Low cloud, rain, low visibility. Ah well, it is nice to be cool.
The road here was built in 18 months during the mid-1850's as the Gold Rush gained momentum. Canterbury, the provincial capital away on the east coast was very keen to have fast communication with the booming, competitive and riotous towns around the gold fields. It's a precipitous, unstable environment, subject to frequent rock-slips as well as torrential waterfalls when it rains. The nearer of the two structures you can see on this cliff-edge stretch of the road is actually guiding a waterfall, known as Reid's Fall, so it crosses the road to fall into the river below.
It is called Arthur's Pass after the European who first established this route across the Divide. It was of course well known to the Maori. Sir Arthur Dobson, along with his father and brother were important surveyors and engineers of the time. When brother George was asked to determine the route for the new road, he is said to have exclaimed that 'Arthur's Pass' was the best, and the name has stuck.