ɚɹˈɪdʒɪnəli, ðə mˈeɪn kˈæmpəs wʌz bˈɪlt ɪn nˈaɪntiːnhˈʌndɹɪd nˈaɪnti fˈaɪv baɪ hˈɛstɹʌp ænd ɐsˈoʊsɪˌeɪts æz ɹˈɛdlɪŋ mˈɪdəl skˈuːl wɪð ɐ kəpˈæsᵻɾi ʌv wˈʌn θˈaʊzənd θɹˈiːhˈʌndɹɪd; ɪn nˈaɪntiːnhˈʌndɹɪd nˈaɪnti nˈaɪn tˈuː θˈaʊzənd ɪt wʌz ɛkspˈændᵻd ænd kənvˈɜːɾᵻd ˌɪntʊ sənt. tʃˈɑːɹlz sˈɛkənd hˈaɪ skˈuːl æɾə kˈɔst ʌv dˈɑːlɚ fˈoːɹɾi wˈʌn,sˈɪkshˈʌndɹɪd,zˈiəɹoʊzˈiəɹoʊ zˈiəɹoʊ.
Originally, the main campus was built in 1995 by Hestrup & Associates as Wredling Middle School with a capacity of 1300; in 1999–2000 it was expanded and converted into St. Charles' second high school at a cost of $41,600,000.