The Alderney safehouse is one of the Niko's safehouses. It is given by Pegorino capo Ray Boccino, after Niko was working for him alot, he decided Niko would want to stay in Pegorino territory even more, which is Alderney. It is located in Alderney City, near the Booth Tunnel. It is pretty basic, like the first two Niko gets. It has a post-bed, a not-so working TV, a greasy-splattered kitchen, and a ruined sofa. Various things too can be found here, such as stacks of newspapers and a phone book.
You get this after you complete all of Ray Boccino's missions, along with completing Phil Bell's mission Truck Hustle.