Using maps to locate your ancestor's village in Prussia and Lithuania can provide important information about their life and where to find records that may exist. Of course, so many changes happened to borders and the village/town names themselves, finding the location on a map can be extremely overwhelming and confusing--especially if you're trying to use modern maps. That's where the magic of Kartenmeister.com comes in.
The site gives you the ability to search village names or, you can view the maps themselves, which are broken up by the Kreis/Districts from 1918. This page here is the starting point for both East (Ostpreußen) and West (Westpreußen) including the boarder towns in Lithuania (such as Wilkowischken and Suwalki.)
If you're unsure about the original spelling of the village or city, Google will likely be a great help. If that doesn't work, try posting for help in the Lithuanian Global Genealogical Society or Ostpreußen / Westpreußen / Pommern pages.