On December 16, 1908, they began construction on the Olympic, the first of the three vessels, in Harland & Wolff's number two slipway. Over three months later, on March 31, 1909, they began construction of the future Titanic in the number three slipway. The Olympic and Titanic were sister ships, nearly identical in their construction. The Olympic was completed by the end of May 1911, just seven months after her hull was launched. This was no average accomplishment considering that Harland & Wolff was simultaneously working on six other liners, two other White Star ships (Nomadic and Traffic) for use at Cherbourg, the P&O liner Maloja, the Aberdeen liner Demosthenes, the Union-Castle intermediate liner Galway Castle, and White Stars mammoth Titanic. Out of Harland & Wolffs work force of 14,000, nearly 4,000 worked on the Titanic.
The Titanic was fully framed on April 6, 1910, a year after the keel had been laid. Plating was completed by October 19, 1910. On May 2, 1911, the Olympic underwent her trials in the fitting-out basin and her mighty engines turned for the first time. If there was any apprehension among the Harland & Wolff hierarchy, it quickly evaporated, as the preliminary test proved satisfactory. Later in the month, before leaving for her trials at sea, the Olympic was opened to the public for five hours. Thousands of people paid 5s, a days wages for many (Harland & Wolff employees were paid 2 pounds for a 49-hour week), to look over the magnificent new liner. It was all for good cause, because all the proceeds were going to local Belfast hospitals.
On the morning of May 29, 1911, the Olympic, fueled by 3,000 tons of best Welsh coal and assisted by five tugs, headed off for two days of sea trials on Belfast Lough. She was accompanied by the new White Star tenders Nomadic and Traffic and, although the results of the tests were not made public, the engineering press cautiously reported that she had exceeded the design speed of 21 knots by three quarters of a knot. The Board of Trade was certainly satisfied with her performance and its Belfast surveyor, Francis Carruthers, promptly issued a certificate of seaworthiness valid for one year. RMS Olympic was now ready to enter service.
Half a million solid iron rivets, fitted hydraulically and weighing 270 tons, were used just on the bottom of the Titanic, with a total of three million fitted on the whole ship. No expense was spared during the construction of the Titanic, especially where strength was concerned. The seams of the bottom platting were double-riveted and those on the topside plating were triple and quadruple-riveted.