Question: Which principality did the man, after which Ranier III Nautical Stadium is named, rule?
Sentence (from "Rainier III, Prince of Monaco"): Rainier III (born Rainier Louis Henri Maxence Bertrand Grimaldi; 31 May 1923 – 6 April 2005) ruled the Principality of Monaco for almost 56 years, making him one of the longest ruling monarchs in European history.
Relevant evidence: Yes