The "Meyers," first published in 1912 is a comprehensive gazetteer of the former German Empire. Valuable as its contents are -- listing every town, village and hamlet -- it is admittedly difficult to use.
The site is an online version that allows wildcard searches for your place of interest in Germany or Poland.
When you get a hit, the original "Meyers" entry is shown as well as a readable and defined translation. Tabs allow you views of the ecclesiastical environment, a historical map that can be toggled with a modern version, and more.
At the top of the landing page is a help tab that is worth your time to read over before launching into a search.
This is a great resource for those doing German/Poland research for the early 20th Century time-frame.