FILE PHOTO: The Iron Throne is seen on the set of the television series Game of Thrones in the Titanic Quarter of Belfast, Northern Ireland, Picture taken June 24, 2014. REUTERS\/Phil Noble\/File PhotoLOS ANGELES (Reuters) - Some 17.4 million Americans watched the first episode of the final season of television\u2019s \u201cGame of Thrones\u201d - a record audience for the medieval fantasy series, cable channel HBO said on Monday. HBO said Sunday\u2019s broadcast audience, including on its HBO GO and HBO NOW apps, exceeded the previous series high of 16.9 million viewers for the Season 7 finale in 2017. On social media, Sunday\u2019s premiere was also the most-tweeted-about episode of the show ever, with more than 5 million Tweets, and 11 million mentions throughout the course of the weekend, HBO said in a statement. All of the top 10 global Twitter trends late Sunday evening were about the episode. The series set among warring families in the fictional kingdom of Westeros, which began in 2007, has become HBO\u2019s biggest hit. Season 7 averaged 32.8 million viewers per episode when delayed viewing was counted. \u201cGame of Thrones\u201d is available in over 150 countries worldwide, but HBO said viewing data is not easily retrieved in many of those markets, making a global figure impossible to calculate. Reporting by Jill Serjeant; Editing by Leslie Adler and Tom BrownOur Standards:The Thomson Reuters Trust Principles.