The first tower, Republic Plaza I, has 66 floors and a height of 280 metres (920 ft), and has a varying octagonal-cross section, while its interior allows for flexible space usage by tenants.

Initially conceived by Jones Lang Wootton in the mid-1980s, development of Republic Plaza was to be carried out by a joint venture between C. Itoh, Land Equity, and several other Japanese firms.

Plans for the second tower were drawn up after a change in the gross floor calculation by the Urban Redevelopment Authority in 1993 allowed for its construction without additional development charges.

It comprises a moment-resisting frame and a central core, and has a varying octagonal cross-section, with the longer sides on the upper floors turned 45 degrees from those at street level.

[9] The complex also includes a three-floor, 241,000 square feet (22,400 m2) retail area,[10] and its basement is linked to Raffles Place MRT station.

[13] The development comprised 3 blocks of 62, 11, and eight floors, and was to occupy a 7,800 square metres (84,000 sq ft) site bounded by Malacca, Cecil, Market, and D’Almeida streets.

[14] In the same report, The Straits Times mentioned that the joint venture was planning to take over two plots on the Republic Plaza site from the Overseas Chinese Banking Corporation and Great Eastern Life.

[18] While negotiations with CDL were underway, the C. Itoh-Land Equity joint venture continued acquiring land for Republic Plaza, purchasing five plots on the development's planned site in December 1987 for about S$64 million.

[25] JLW, which acted as the development's marketing agent, had started negotiations with several potential tenants by June 1994,[26] and the building's steel frame was completed in December 1994.

[29] In addition, in accordance with the 1988 agreement made between the partners, CDL bought out C. Itoh's and Shimizu's stakes in the development in February 1996 for S$47.1 million.

[34] ING and Itochu moved out of Republic Plaza in the third quarter of 2017, followed by Bank of Tokyo-Mitsubish UFJ, until then the building's main tenant, by the end of that year.