The Spanish national anthem, Marcha Real, has never officially had lyrics and has been played without any unofficial words since 1978. – WTF Fun Facts
Source: https://quizzclub.com/trivia/the-spanish-national-anthem-has-no-words/answer/496/
WTF Fun Fact – Wordless National Anthem
Official anthem since XVIII century, except for 3 short periods https://es.wikipedia.org/wiki/Marcha_Real