Edited by Saturn on November 5, 2015 2:45PM
Thanks to @Padhraigh
who I worked together with to find all of these locations.
First here is a link to the thread that started our exploration:
Go to the thread above if you don't want spoilers about where all the items are, but just hints to some of the difficult ones.
In this spoiler is a crude map of all the locations I made using paint, but you might want to use it in conjunction with Padhraigh's original post if you have troubles finding the exact spot:
Credit also has to go to @mlstevens42_ESO
who found the Centurion's Signet, which was probably one of the hardest ones to find.
I also made a video guide that shows you how to get all 20 Relics along with another museum item called Armlet of Torug (Note that the Armlet is not needed for the achievement):
If you use any of this information to make a map of your own or something similar, please make sure to credit @Padhraigh
To find out how to get the three House of Orsimer Glories costumes go here
I also have a video below of the last museum quest:
"Madness is a bitter mercy, perhaps, but a mercy nonetheless."
Fire and Ice