The phrase "a most fascinating" is correct and usable in written English.
It can be used to emphasize the degree of fascination regarding a subject or topic.
Example: "The documentary provided a most fascinating insight into the lives of ancient civilizations."
Alternatives: "a truly captivating" or "an exceptionally interesting".
I've written rather more than half of a most fascinating (to me) novel.
The most rare and valuable single bronze, he said -- and I would add a most fascinating object to scrutinize -- is the ornate bronze ceremonial wine vessel prominently displayed near the entrance, with the face of a deity and various birds and other figures and a gorgeous blue-green patina.
Disc Two features a most fascinating behind-the-scenes look called "Rehearsal Process," which allows Streisand fans and film students alike into her creative world.
It is a most fascinating, confounding and elusive medium and being so embedded in every aspect of modern society, it has the ability as an art form to address all the issues that face us as humans on this planet.
Add in that he was a most complex character, alternately prim and shy and crude and outgoing, as well as being a public figure and a homosexual at a time when being the latter was still illegal in most states, and you should have the subject of a most fascinating biography.
One man, a controlling, type A, had the most fascinating response.
But it is the internal processes of this group of determined individualists that Tal Alon, a journalist, finds most fascinating.
Included are a zither and a gaming table, but most fascinating are objects notable for their delicacy: diaphanous hats made of black horsehair, a hatbox that looks like a Tiffany lamp, and a white cloth for wrapping clothes.
But Killgrave is too pathetic, too undeveloped a character to be entirely convincing as a villain and the most fascinating element of Jessica Jones is the struggle around agency.
Most fascinating is Appendix A, which features the film projects Kubrick started but never shot.
However, with Split, despite being a horror-thriller, the most fascinating moments are the ones McAvoy spends on Dr Fletcher's couch.
