Halacha codifies making a blessing on wondrous natural events and places (see here). I would like to know if any halachic authorities discuss making a blessing on wondrous man-made structures such as the Great Wall of China or the Large Hadron Collider
Not that I am aware of and the Artscroll siddur also doesn't mention it.
R Shlomo Aviner was asked whether one should make a shechechiyanu blessing regarding the new tunnel on the Yerushalayim-Tel Aviv road (of course it pales in comparison with the Great Wall or LHC!)
Q: There is a new tunnel on the Yerushalayim-Tel Aviv Road which greatly eases the traffic. Is it permissible for me to recite Shechechiyanu when I drive through it for the first time?
A: It does not seem so, since this is not included among the general rules for reciting this blessing. See Shulchan Aruch, Orach Chaim 222-223. Perhaps one may recite it if he is happy, since it is "good news" (ibid. 222:1), but it does not seem so.
If there was an appropriate blessing for a man-made creation R Aviner would surely have mentioned it.