The Imperial Hotel is quite large, and easily locatable opposite the Square itself, at the end of Southampton Row just as the road becomes "Russell Square" (Arrow above)

61-66 Russell Sq,
London, WC1B 5BB‎                 

Underground: Russell Square station on the Piccadilly Line is close to all the hotels and stops at Heathrow Airport, Covent Garden, Leicester Square, and Knightsbridge (Harrods).

Train: King’s Cross, Euston and St. Pancras Stations are a short walk from the hotels.

Car: There is underground (pay) parking at the Imperial, Royal National, President and Bedford Hotels with Congestion Charge payment points.