The Kamensk military base is located in the north of Chernarus, near the city of the same name. The base itself is unmarked and can be easily missed if you don't pay attension. It lies to the east of Kamensk and directly north of Severograd. The base is mostly left untouched as it is very well hidden.
This base previously had a different layout, with 4 giant stone hangars and the prison & barracks buildings were beside each other.
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The "Lost" Underground
There were once several underground areas at this base, which became sealed off as of 0.57. One still remains in the southeast corner, but it cannot be accessed. The other three are gone indefinitely, but have been preserved here with their own article.