More years ago than I care to report, one school 6th form trip was a horse-drawn barge across these two aqueducts (history master was an old transport buff), which was fascinating. The towpath is on the west side, none too wide, but does have a handrail. The east side has nothing and the top of the channel is not much above water level. Great for leaning over the side I've just recalled as I write this that said history master lost the lens cap from his camera over into the valley below (large cheer inevitable).

If coming from the north a taxi from Ruabon station down to the bridge will not be too expensive, it's just a couple of miles. There are pubs at both ends (no, we didn't sample them on the 6th form trip - I've been back recently to look again !)

You could go via Ruabon and taxi to the north end, walk across, then taxi from the south end to Chirk. But the best would surely be to go over by boat. I'm sure that horse trip still operates because I've seen it on the television in recent times. Or, if you have the chutzpah, you could ask a passing narrowboat for a ride.