St. John's Episcopal Church is New Castle's oldest existing church. The building's cornerstone was laid on November 2, 1908, and the first service was held on Easter Sunday, April 11, 1909. The exterior has changed very little since construction. Typical of small-town churches built in the Gothic Revival style, it features concrete construction, a gabled roof, square wood shingles, and pointed arch windows. It was constructed using local labor and materials. The church's Guild Hall across 1st Street was a Civilian Conservation Corps building and was moved from La Junta, Colorado, to its current site in 1948.