From the outside, the main façade and the sides of the building present evident details of its affiliation to the "beaux arts" style , a style that is characterized by symmetry, large entrances, staircases, polychrome and a great profusion of balustrades, supporting cornices or bas-relief panels. Among all of them, the roofs and mansards are the most beautiful example.

But it is inside and throughout its 6 floors where his work acquires the splendor that has given it such just fame. It was also the first hotel in Spain to integrate toilets into the rooms . In fact, one of its first slogans was "Hotel Carlton 200 rooms, 200 bathrooms." The architect of Basque-English origin designed a large space, a central hall, covered by a beautiful leaded stained glass window through which a cozy light filters. This glass window has been the symbol of the Carlton Hotel over time, and after a respectful renovation, it continues to represent the hotel's classicism.

The conjunction of all the values mentioned above led the Basque Government to declare it an architectural, historical and cultural monument in 1995. This recognition has only strengthened the prominence of the Carlton Hotel in Bilbao.

The Carlton Hotel has been a witness to important social and cultural events that have occurred in the contemporary history of the Basque Country.

The hotel was the headquarters of the Basque Government during the Civil War , a circumstance that can still be seen today in two places in the hotel.

The first is one of the rooms, the Luis García Campos Room. It was the center of debates and operations of the Basque government in 1936, when José Antonio Aguirre was its president. As a curiosity, in said room the only saved glass window is preserved, in addition, the presidential table and two of its chairs are still preserved.