Complex sentence: This severe almost startling form of neoclassicism had become popular in the first decade of the 19th century and was pioneered by such architects as Peter Speeth and Friederich Gilly and is in contrast to the more elegant neoclassicism of such architects as Robert Adam and John Nash.
Split into simpler sentences: This severe almost startling form of neoclassicism had become popular in the first decade of the 19th century. It was pioneered by such architects as Peter Speeth and Friederich Gilly and is in contrast to the more elegant neoclassicism of such architects as Robert Adam and John Nash.