A bit of a UK theme today but perhaps there are international analogies?
I am sorry (or relieved?) to say I have recently discovered there are more geeks out there than just me. More people who actually think staring at benchmarks or trig pillars is quite thrilling. OK, park us in the 'must get out more' club but humour us please.
You can check out the UK benchmark database. The OS is pretty hands-off with respect to benchmarks but, correctly, states that you can't rely on them for vertical positioning and should use GPS heighting instead. Or have a hunt around here. Or at Fayers.
And while I was hunting around looking for benchmarks I came across something even better. Check out the British Isles by geo location.