The first area contains many common Dwemer artifacts that are directly on display or are in display cases. However, if the key was obtained by stealing, the guards will be hostile. After entering the museum, the guards will not be hostile if Calcelmo's quest is completed, or if he was bribed, intimidated, or persuaded. If Nimhe has not been killed, the guard at the door will tell the Dragonborn that they are not allowed to go in, but after the dialogue the guard will allow entrance into the museum. Once the key to Calcelmo's Museum is obtained, head to the North wing of Understone Keep and enter the museum. After the conversation with him, they must travel to Markarth and speak to Calcelmo at Understone Keep - he will not grant them access to his research unless persuaded, bribed, intimidated or if they have helped him out by completing the temple quest " The Book of Love," the Dragonborn has completed the side quest to kill the spider Nimhe in the excavation site, or just simply sold him any piece of Dwemer equipment that he requested.
Unfortunately, the journal is written in some sort of code that need to be deciphered. Karliah believes the only proof that could expose Mercer's treachery can be found within the pages of Gallus' journal which she recovered from Snow Veil Sanctum.