He was then eighteen years of age. Following two years of training under Mr. Smith and a subsequent period with Henry T. Brush (one of Detroit’s early practitioners), Mr. Mason left for an extended visit in Europe. While pursuing his studies in architecture and the fine arts he traveled extensively on the continent, and upon his return to Detroit in 1878, prepared to launch his professional career.
In association with Zacharias Rice he opened an office under the firm name of Mason & Rice, and continued that partnership until 1898. For a number of subsequent years Mr. Mason carried on an independent practice, then early in the 1920's organized the firm of George D. Mason & Company, when former members of his office, Albert C. McDonald, David H. Williams, Jr. and Her¬bert C. Wenzell, were taken into partnership.
During his long years of practice, Mr. Mason (under his own name or with associates) designed many buildings of varied types, including churches, hotels, public buildings of note, and business and commercial structures. Among his most important works in Detroit were the Y. M. C. A., one of his earliest buildings, completed in 1886: the First Presbyterian Church, 1889 and the Trinity Episcopal, 1893; the old Masonic Temple, 1893; City Opera House, 1898; Temple Beth-El, 1902; Pontchartrain hotel, 1907; Fire and Marine Insurance Building, 1911; new Lincoln Motor Company Plant, 1917; Yacht Club, 1920; Third Church of Christ Scientist, 1921; Highland Park Trinity Methodist Church, 1921, and the Pilgrim Congregational Church, 1923; the new Masonic Temple, built between 1922 and 1926, at the time of its com¬pletion the largest fraternal building in the world; Broadway Chambers, 1926; Standard Savings and Loan Association Building, 1927; Central Woodward Christian Church, 1931 (awarded the Medal of Honor of the Detroit Chapter, A. I. A.) ,and in 1931 the Brewster and Parksite Housing Projects, designed by a group headed by Mr. Mason.
In addition to work in Detroit he planned a number of buildings in other locations among which was the Grand Hotel on Mackinac Island, Mich., 1887; Office Building for Hiram Walker & Sons, Walkerville (Ontario), Canada, 1892, and at Dearborn, Mich, the City High School and Masonic Temple, 1926. In later years, 1934-48, his firm was commissioned to design St. James Lutheran Church, Dr. Pitcher s Elementary School, and the Mayflower Congregational Church, Grosse Point, Mich.
Throughout the various phases of his long career in architecture, Mr. Mason and his colleagues did work of high excellences, both in design and construction. He was much interested in the work of architectural schools, and one of the first Michigan architects to seek and employ graduates.
Early in his practice he became a member of the Michigan State Association of Architects, and before 1887 was affiliated with the old Western Association of Architects. After being elected a charter member of the Michigan Chapter, A. I. A. in 1887, he was transferred to the Detroit Chapter in 1898, and became successively an Associate of the A. I. A., a Fellow in 1892, and member Emeritus in 1946.