As far as I'm aware of, a lot of models in particle physics and in the so called grand unified theories postulate the existence of magnetic monopoles. When I was an undergraduate student I always thought that it was fascinating that so much could be built theoretically without the CONCRETE evidence the for existence of monopoles (maybe indirect evidence - the models seem to work). Isn't that a little bit of an embarassing thing? I have the impression that it is as embarassing as people can feel about "the measurement problem" in quantum mechanics.... According to wikipedia (I know a article would be a better source, but I do not have the one they used): "The most recent such experiments [experiments made to detect very massive particles like the magnetic monopole] suggest that monopoles with masses below 600 GeV/c² do not exist, while upper limits on their mass due to the very existence of the universe – which would have collapsed by now if they were too heavy – are about 10¹⁷ GeV/c²." So, roughly 15 to 14 orders of magnetude which are kinda difficult to probe (especially the 10¹⁷ end because it is just two orders of magnetude away from the Planck mass which is approximately 1.22*10¹⁹ GeV/c²). This could suggest a layperson like myself that there could be low hopes of observing those particles in our future particles accelerators - but it could happen tomorrow (if it does do not refrain from telling me, I WILL WANT TO KNOW ABOUT IT!!!!!!)... So the question that we have in our hands is this: How would YOU detect magnetic monopoles? Please, focus on the reproductibility of the experiment. If your experiment can only be performed once I'll consider it a failure - now that I threatened, you know I'm speaking seriously (no really though). I want to see the answers while I also would like to give suggestions on how I would plan on observing such thing - and I want people to tell me why my impressions about this are wrong (I do not know anyone very versed in the particle physics stuff to discuss that with them... and the people working were I work are almost as ignorant about it as I am myself, I'd dare say).