kənstɹˈʌkʃən ʌvðə fˈɜːst sˈɛɡmənt stˈɑːɹɾᵻd ɪn nˈaɪntiːnhˈʌndɹɪd sˈɛvənti θɹˈiː, pˈɑːɹt ʌv ðɪs sˈɛɡmənt wʌz ˈɔːlsoʊ ɐ tˈʌnəl kənˈɛktɪŋ ðɪs lˈaɪn wɪððɪ ɔːlɹˌɛdi ɛɡzˈɪstɪŋ lˈaɪn sˈiː bᵻtwˌiːn mjuːzˈiːəm ænd nˈeɪmsti mˈɜːɹuː stˈeɪʃənz.
Construction of the first segment started in 1973, part of this segment was also a tunnel connecting this line with the already existing Line C between Muzeum and Náměstí Míru stations.