How many letters does the top answer for “home of union buildings” have?

The most common answer is pretoria (8 letters).

Crossword clue: home of union buildings

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

pretoria 8 letters wd-fact-v3

city in the Transvaal; the seat of the executive branch of the government of South Africa

home of berlaymont building 50% similar → brussels

home of europa building 50% similar → brussels

home of house of the unions 50% similar → moscow, tverskoydistrict

home of lloyd's building 50% similar → cityoflondon

home of lubyanka building 50% similar → krasnoselskydistrict

home of secession building 50% similar → innerestadt