Complex sentence: They renovated the first floor to resemble what it originally had looked like after White first built it; they created offices on the second and third floor for their own personal use, and used the top floor to lease to professional offices.
Split into simpler sentences: They renovated the first floor to resemble what it originally had looked like after White first built it. They created offices on the second and third floor for their own personal use, and used the top floor to lease to professional offices.