How many letters does the top answer for “city in upper austria” have?

The most common answer is linz (4 letters).

Crossword clue: city in upper austria

3 answers found in Letterora's clue database (Wikidata facts, Open Trivia DB, WordNet and Webster definitions — all licensed sources).

linz 4 letters wd-fact-v3

city in northern Austria on the Danube; noted as a cultural center

steyr 5 letters wd-fact-v3

wels 4 letters wd-fact-v3

The sheatfish; -- called also waller.

city in lower austria 50% similar → carnuntum, krems, waidhofenanderybbs

city in upper bavaria 50% similar → eichstatt, munich

city in upper hutt city 50% similar → upperhutt

city in upper nile 50% similar → malakal