Hello Gerald!
Like Marina told you perfectly, "de" is a mistake. The right text would be:
"El museo se compone de dos edificios: el primero de ellos data del siglo XVI y era el antiguo hospital San Carlos; el segundo se construyó en 2001 y es obra del prestigioso arquitecto Jean Nouvel."
I think that you don´t understand this "El museo se compone de dos edificios", because in English you use "The museum is made up of two buildings" is like the passive voice, but we use "the impersonal form" or we can also say "El museo está compuesto de dos edificios" but it´s more common to say "El museo se compone de dos edificios"
I hope I´ve helped you!! Greeting from Spain!!