Besides Poland, the Czech Republic contains a portion of historical Silesia. AFAIK Germany does too.

The largest city in the Czech portion of Silesia is Ostrava, traditionally linked to heavy industry; the city is highly polluted and has problems with mines leading under the city itself, causing, for example, ground sinkage problems.

One easy place to find a mildly distorted featureless map of Silesia is the map for the game Diplomacy.