The richer and more industrialised south-western states of Germany are ususally preferred by immigrants. This is seen as still related to the division between East and West Germany before unification: to overcome shortage of East Germany workers after the erection of the Berlin Wall in 1961, West Germany extablished bilateral agreements with southern countries where unemployment rates were high, so that guest-workers (Gastarbeiter) from these countries would move to and work in Germany industrialized hubs. The intent of the proprams was that these residents would stay in Germany only temporarily, but the reality is that, together with their families, they became permanent residents.
The big numbers of Turkish immigrants in Germany and in Berlin – where we can find the biggest Turkish community outside Turkey – are directly linked with the guest-worker programm.

Today, the majority of Portuguese migrants (first and second generation) reside in the states of North Rhine-Westphalia (26.1%), Baden-Württemberg (20.1%) and Hessen (10,5%).

In Berlin, where the Wall devided the city in East and West Germany, we can find a microcosmos of Germany as a whole, with the West part of the city being more affluent and cosmopolitan than the East. Mitte, in the historical centre of Berlin is the district with a higher percentage of immigrants, both first generation (green in the map) and second generation (dark blue). The West districts of Charlottenburg-Wilmersdorf and Neukölln also have high rates of foreign born population, with the East districts of Marzahn-Hellersdorf and Treptow-Köpenick having the lowest rates. EU nationals (of which we excluded Poland because of its overbarring weight in proportion to other EU countries) generally follow this tendency. There is no data for Portuguese migrants.

https://www.statistik-berlin-brandenburg.de/publikationen/Stat_Berichte/2018/SB_A01-05-00_2017h02_BE.pdf