The cornerstone of the luxury hotel was laid on August 15, 1936, by King Carol II. The construction of the sumptuous building, designed by George Matei Cantacuzino, an architect of the Romanian Railways, lasted only two years.The hotel is 600 meters away from the beach facilities. It stretches over 2,000 square feet, along the beach; there are 120 rooms on the ground floor. The technique and decoration gives the apartments, the hall, the reading room and the restaurant hall a special charm that this hotel will be the most modern and comfortable building on the Black Sea coast.
By Royal Decree 322 of 29 February 1936, amended by Decree Law 3047 of August 31, 1938, the "Law on the Organization of Tourism" was promulgated. This law has created a body designed to operate in the field of hotel construction and to give as much as possible the development of tourism to Romania, a body first called the "Romanian Railways Hotel Committee" and then "The Special Committee of Hotels". This body, chaired by the Ministry of National Propaganda, includes within it delegates from the Tourism Directorate, the Autonomous Regime of Romanian Railways and the Ministry of Air and Navy. By the cited law it is established that both the rules for the administration of the funds and for the execution of the respective works will be those applied by the Autonomous Registry Romanian Railways, the activity of this Committee being executed by the staff of this Administration. The Committee of the Hotels Committee, which amounts to 55 million lei annually, is provided by the Romanian Railways Administration, which obtains through a 2% levy on travel tickets on its network. The Hotel Committee's work has been directed, according to an overall program, to the construction and arrangement of tourist hotels. Thus, the Rex Hotel in Mamaia, the Delta Hotel in Vâlcov and the Danubius Hotel in Turnu Severin, as well as a number of tourist inns were built. These hotels are owned by the Romanian Railways.
Since 1935, King Carol II proposes to set up a special tourist agency under the auspices of the government. In order to ensure a unitary leadership of the main tourist companies in Romania, the "Federation of Romanian Tourism Societies" was established, the supreme supervisory and controlling force being the National Tourist Office. By law of February 29, 1936, the "National Tourist Office" was established within the Ministry of the Interior. The ONT has, from the outset, set up, besides a tourism organization program, the help, guidance and co-ordination of private tourism activities, the construction of hotels, as well as any endowment works useful to tourism. A first list included the construction of hotels in Mamaia, Vâlcov, Turnu-Severin, Sarmizegetusa, Balcic, Predeal, Danube Delta etc. The accent was put on the hotel in Mamaia, which wanted the most modern comfort: 126 rooms, each with bathroom, restaurant, bar, reading rooms, dance, beach. The Hotel Committee's funds, amounting to 55 million lei annually, were provided by the Romanian Railways. Administration, being obtained by taking 2% of the ticket price. Through this program, the Rex Hotel in Mamaia, the Delta Hotel in Vâlcov and the Hotel Danubius in Turnu Severin, as well as a number of tourist inns, all of which are the property of the Autonomous Administration of Romanian Railways.
In this context, the City Hall has been associated with the National Tourism Office for the construction of the high capacity hotel. Capşuneanu's project was abandoned and the architect George Matei Cantacuzino, who at that time was Chief Architect of the Romanian Railways, was chosen by the National Tourist Office. The site was chosen according to the last planning and organization plan of the resort, which established the alternation of private villas with public amenities, large parks and hotel units.
G. M. Cantacuzino chose architect Vasile Arion to accompany him to the project, and both were present at Mamaia on August 15, 1936, when King Carol II laid the foundation stone of Rex Hotel. The hotel, built in modernist style, was finished in 1938 and was immediately cataloged as a luxury hotel.
The facilities and facilities - the access roads, the park in front of the hotel, the water and electricity supply - were supported by the Constanţa City Hall. On July 9, 1938, the Council of Hygiene and Protection of the Municipality of Constanta discusses the application for authorization for operation of the Grand Hotel REX in the resort of Mamaia. The Council approves the application, provided that the petitioner complies with the decisions in force and pays the 10,000 lei tax to the Sanitary Fund. After the commissioning of Hotel Rex, it was decided to extend the railway line for the passengers to the REX area. The Rex Station building still exists today, but it has the club function.
It would be interesting to say that Arch. Cantacuzino (author of several modernist buildings on the Romanian seaside during the interwar period - such as Bellona Hotel in Eforie Nord) has also designed a mega-complex on the Rex Hotel. This complex would be followed by another hotel, symmetrically disposed to a second Casino, much larger than that of the Victor Victor Ştephănescu, Hotel Rex being just a wing of the complex. Perhaps this complex would have happened if World War II did not intervened
In the communist period, on June 15, 1945, the summer season was reopened, and the REX Hotel was renamed Rest House "1 Mai". On 1 December 1958 HCM of RPR was issued for the transfer of goods from Mamaia Resort to the Carpathian National Tourist Office, including the "1 Mai" (formerly REX Hotel), and the Mamaia Hotels and Restaurants Enterprise - IHR Mamaia.
After 1960 the hotel was named "International", a name preserved until 1990. It contained 128 rooms with 228 seats. In 1974 the Constanta County Institute of Design was created, another project for the modernization of the International Hotel. The central body of the beach on the ground floor was dismantled and it was rebuilt to larger dimensions for the location of an outdoor pool with large terraces on the mezzanine floor and the kitchen on the ground floor expanded. The central body, initially covered with a terrace, was made of a two-aisle and ocean roof, as is the hotel today
After 1990 O.N.T. Mamaia turned into S.C. Mamaia S.A., taking over its patrimony, including the International Hotel, which returned to the original name "Grand Hotel REX". In August 2006, Grand Hotel Rex was bought by "Tycoon Imobilar", which invested to bring it to Western standards with five-star service and comfort for luxury vacations or business meetings. On the night of 17 to 18 February 2011 and the following night, while the hotel was closed, it was affected by a fire beginning in the area of the bridge and the stairwell, which destroyed the roof across its entire surface and descended to the lower floors through the columns of ventilation. The extinguishment was difficult due to the strong wind, and the large amount of water used damaged all the interiors of the hotel, with their finishes, furniture and equipment. After this incident, in August 2011, Hotel Rex broke away from the parent company, Tycoon Imobiliar, by dividing the latter, being taken over by the company "S.C. Rex Mamaia S.A. "
Starting in 2014, the historic park in front of the entrance of the REX Hotel, abandoned, has been lowered, with more than half of it being built, parking spaces. The hotel, although it has a site that invites you to spend your holidays in it, is today inoperative, the refurbishments are not finished even after four years.