The 15th degree east longitude line crosses through many countries and counties. It's impossible to list every single county, as that would be extremely lengthy.

However, I can tell you the countries it passes through, and you can then find the counties within those countries:

Countries Crossed by 15° East Longitude:

* Europe:

* Norway

* Sweden

* Denmark (passes just west of Copenhagen)

* Germany

* Czech Republic

* Austria

* Slovenia

* Croatia

* Bosnia and Herzegovina

* Montenegro

* Albania

* Greece

* Africa:

* Algeria

* Libya

* Niger

* Chad

* Central African Republic

* Democratic Republic of Congo

* Republic of Congo

* Angola

* Namibia

* Botswana

* South Africa

* Antarctica:

* Queen Maud Land (claimed by Norway)

To find the specific counties within these countries:

1. Locate the 15th degree east longitude line on a map. This can be done using online mapping tools or a physical atlas.

2. Identify the countries the line passes through.

3. Research the administrative divisions of each country. This may involve looking up county or region information on government websites, online encyclopedias, or geographical databases.

This approach will allow you to determine the specific counties that are crossed by the 15th degree east longitude line.