My boss collects things. Mostly documents that have a monetary or historical value. He has ones that are preserved in glass cases. The inside space is filled with a special gas, and the glass prevents any ultraviolet light damage. He has pieces that are very valuable down to ones that are not. He needed extra space to store some of the documents, and I recommended he check out http://www.store-friendly.com.sg for their secure storage areas in the facilities they have all over Singapore. I use their regular storage lockers, but they have spaces that are climate controlled and have CCTV security cameras.
My boss thought it was a regular personal storage place. I told him that it is, but they also have secure storage too. I explained how he could access the security camera feeds from a remote location to be able to check on his stuff at any time he wished. He started out by moving a few of the lower value items to the storage facility. Then after he was comfortable with the security and access control systems that were in place, he began to add some higher value items. He ended up renting almost all of the secure storage space at one of their facilities. He has not had any problems.
He even bought a standalone climate recording device he checks from time to time. It records temperature and humidity levels. The climate control of the area he rents in the storage facility is always within the guidelines of what is needed to protect the documents from damage. He is extra careful like that. The other day we moved another of the pieces inside one of those special glass cases to the storage facility. He trusts the storage space now that he has seen there are no problems. I just have regular stuff stored I use seasonally. He has high-value items stored there. They provide for the needs of each customer.