[8] Owing to Liverpool being a major arrival and departure point for ocean liners during the early 20th century, the Adelphi served as the most popular hotel in the city for wealthy passengers before they embarked on their journey to North America.

[9] The RMS Titanic was registered in Liverpool (though it never visited the port), and the Sefton Suite is said to be an exact replica of the ill-fated liner's First Class Smoking Lounge.

Guests at the hotel from this period included world leaders, such as Franklin D. Roosevelt and Winston Churchill; as well as music artists like Frank Sinatra, Laurel and Hardy, Judy Garland, Bob Dylan, and Roy Rogers.

Following the Conservative Party's victory in the 1979 general election, British Rail was ordered to dispose of unnecessary assets.

[12] It was handed a fourth consecutive zero in its food hygiene rating after an inspection in January 2016,[13] and in June 2017 Britannia Hotels admitted in Liverpool Magistrates' Court to seven breaches of health and safety law and were fined £265,000.

[14] On 30 August 2006 a 25 year old man drowned in the swimming pool of the Adelphi after the lifeguard on duty left his post.

[19] On 4 October, the Liverpool Echo revealed that the hotel is also under investigation for an incident that occurred earlier in 2022 in which a guest was injured.

[1] The Central Court is top-lit, and contains pink marble pilasters, glazed screens, and French doors opening into restaurants on its sides.

[8] In Jules Verne's 1870 novel Twenty Thousand Leagues Under the Seas Chapter 1.8, Professor Aronnax describes the interior of the submarine as similar to the Adelphi Hotel.