According to the Monorail Society website, the first ever passenger carrying monorail was in my home town, at Cheshunt:

1825 — Cheshunt Railway
The first passenger carrying monorail celebrated a grand opening June 25th, 1825. It had a one-horse power engine … literally. Based on a 1821 patent by Henry Robinson Palmer, the Cheshunt Railway was actually built to carry bricks, but made monorail history by carrying passengers at its opening.

And I’m pleased to have been on the world’s oldest monorail which is still in operation: the Wuppertal Schwebebahn (above) which is also the only public passenger carrying dangling railway. It is certainly an interesting ride.