Mauretania and Lusitania were both designed by Cunard naval architect Leonard Peskett, with Swan Hunter and John Brown working from plans for an ocean greyhound with a stipulated service speed of twenty-four knots in moderate weather, as per the terms of her mail subsidy contract.
Peskett's original configuration for the ships in 1902 was a three-funnel design, when reciprocating engines were destined to be the powerplant.
A giant model of the ships appeared in Shipbuilder's magazine in this configuration.
Cunard decided to change power plants to Parson's new turbine technology, and the ship's design was again modified when Peskett added a fourth funnel to the ship's profile.
Construction of the vessel finally began with the laying of the keel in August 1904.

In 1906, Mauretania was launched by the Duchess of Roxburghe.
At the time of her launch, she was the largest moving structure ever built, and slightly larger in gross tonnage than Lusitania.
The main visual differences between Mauretania and Lusitania were that Mauretania was five feet longer and had different vents.
Mauretania also had two extra stages of turbine blades in her forward turbines, making her slightly faster than Lusitania.
Mauretania and Lusitania were the only ships with direct-drive steam turbines to hold the Blue Riband; in later ships, reduction-geared turbines were mainly used.
Mauretania's usage of the steam turbine was the largest application yet of the then-new technology, developed by Charles Algernon Parsons.
During speed trials, these engines caused significant vibration at high speeds; in response, Mauretania received strengthening members aft and redesigned propellers before entering service, which reduced vibration.

Mauretania was designed to suit Edwardian tastes.
The ship's interior was designed by Harold Peto, architect, and her public rooms were fitted out by two notable London design houses – Ch.
Mellier & Sons and Turner and Lord, with twenty-eight different types of wood, along with marble, tapestries, and other furnishings such as the stunning octagon table in the smoking room.
Wood panelling for her first class public rooms was supposedly carved by three hundred craftsmen from Palestine but this seems unlikely, unnecessary and was probably executed by the yard or subcontracted, as were the majority of the second and third class areas.
The multi-level first-class dining saloon of straw oak was decorated in Francis I style and topped by a large dome skylight.
A series of elevators, then a rare new feature for liners, with grilles composed of the relatively new lightweight aluminum, were installed next to Mauretania's walnut grand staircase.
A new feature was the Verandah Café on the boat deck, where passengers were served beverages in a weather-protected environment, although this was enclosed within a year as it proved unrealistic.
Mauretania and Lusitania were both designed by Cunard naval architect Leonard Peskett, with Swan Hunter and John Brown working from plans for an ocean greyhound with a stipulated service speed of twenty-four knots in moderate weather, as per the terms of her mail subsidy contract. Peskett's original configuration for the ships in 1902 was a three-funnel design, when reciprocating engines were destined to be the powerplant. A giant model of the ships appeared in Shipbuilder's magazine in this configuration. Cunard decided to change power plants to Parson's new turbine technology, and the ship's design was again modified when Peskett added a fourth funnel to the ship's profile. Construction of the vessel finally began with the laying of the keel in August 1904.
In 1906, Mauretania was launched by the Duchess of Roxburghe. At the time of her launch, she was the largest moving structure ever built, and slightly larger in gross tonnage than Lusitania. The main visual differences between Mauretania and Lusitania were that Mauretania was five feet longer and had different vents. Mauretania also had two extra stages of turbine blades in her forward turbines, making her slightly faster than Lusitania. Mauretania and Lusitania were the only ships with direct-drive steam turbines to hold the Blue Riband; in later ships, reduction-geared turbines were mainly used. Mauretania's usage of the steam turbine was the largest application yet of the then-new technology, developed by Charles Algernon Parsons. During speed trials, these engines caused significant vibration at high speeds; in response, Mauretania received strengthening members aft and redesigned propellers before entering service, which reduced vibration.
Mauretania was designed to suit Edwardian tastes. The ship's interior was designed by Harold Peto, architect, and her public rooms were fitted out by two notable London design houses – Ch. Mellier & Sons and Turner and Lord, with twenty-eight different types of wood, along with marble, tapestries, and other furnishings such as the stunning octagon table in the smoking room. Wood panelling for her first class public rooms was supposedly carved by three hundred craftsmen from Palestine but this seems unlikely, unnecessary and was probably executed by the yard or subcontracted, as were the majority of the second and third class areas. The multi-level first-class dining saloon of straw oak was decorated in Francis I style and topped by a large dome skylight. A series of elevators, then a rare new feature for liners, with grilles composed of the relatively new lightweight aluminum, were installed next to Mauretania's walnut grand staircase. A new feature was the Verandah Café on the boat deck, where passengers were served beverages in a weather-protected environment, although this was enclosed within a year as it proved unrealistic.
RMS Mauretania (1906)