Complex sentence: Kahn was only 22 or 23 years old and had just returned from spending 1891 in Europe, studying the classical architecture of the Old World: his decision to design the home in the French Renaissance Revival style reflected the time he spent sketching the best Gallic architecture.
Split into simpler sentences: Kahn was only 22 or 23 years old and had just returned from spending 1891 in Europe studying the classical architecture of the Old World. Kahn's decision to design in a French Renaissance mode for the home reflected the time he spent sketching the best Gallic architecture.