How many letters does the top answer for “album by mercury” have?

The most common answer is barcelona (9 letters).

Crossword clue: album by mercury

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

barcelona 9 letters wd-fact-v3

a city in northeastern Spain on the Mediterranean; 2nd largest Spanish city and the largest port and commercial center;

thesolocollection 17 letters wd-fact-v3

album by that 50% similar → beautifulworld, everythingchanges, nobodyelse

album by who 50% similar → aquickone, endlesswire, facedances