History of Math
maa.tandfonline.com
maa.tandfonline.com
Something not really for general public, but also not for math PhD.
It's sort of inbetween popsci and Graduate Maths, probably undergrad level. Lots of historical "essays" covering Number Theory, Calculus/Analysis, Proofs etc..
Has some interesting history - apparently Newton developed three versions of his calculus: infinitesimals (geometric approach), fluxions (kinematic approach) and 'prime and ultimate ratios' (algebraic). He used a mix of all three to solve some problems. Never read that before!
Edit: I clicked though and I see that (for me) William Dunham is actually the author of the first article in the list.
If you're no Math PhD but you are mathematically inclined (e.g. I studied plenty of math as an undergraduate but left to play the software industry game thereafter) you should have the errata document handy (I'll link the parent page that has other paratext [1]) - the author is a math enthusiast but not a mathematician and gets some of the finer details incorrect.
I also read Fermat's Last Theorem by Simon Singh and recall liking it, but I can't recall if it holds up under either mathematical scrutiny or the scrutiny of a more refined palate.
[1] https://www.thehowlingfantods.com/dfw/everything-and-more.ht...