What we know
Welsh settlement at the head of West Cherry Creek. Gwillim left Wales about 1869, and his first crop here, in 1871, was 'the beginning of Gwillimville' (Hayes 1879). Cheese factory (1877 or 1878); 75 Welsh colonists in 1879; school dedicated June 11, 1882; church 1893; PO 1878-1890, mail to Monument. 'Bryn Mawr' was the name of Richard J. Gwillim's farm next door (Carrigan 2020). Diphtheria killed children in nearly every family in January 1880 (Gwen Gwillim Clark, in von Ahlefeldt 1979). Richard's house burned in 1895, and the settlement had faded by about 1900. A log cabin and a hay shed said to date from the town still stand on a ranch here (Searle, Tribune, 2019-21). The schoolhouse was moved into Monument about 1930 and out to Highway 105 in 1985, where it still stands as the Chamber's meeting house (Lavelett's 1985 letter, quoted by Carrigan; Our Community News, 2023 and 2026).
Where it was
Wikipedia (approximate). Place Names of Colorado puts it in Sec. 10, T11S R66W, '6 mi E of Monument'; that section's center is about three-quarters of a mile from this point. 1878-79 newspapers: 'five miles distant' from Monument and 'about five miles east of the railroad'. G. R. Gwillim's first patent (Sept. 10, 1873; Sec. 9, T11S R66W, S1/2 SE and NE SE) is about a third of a mile from this point. Charlie Searle (Tribune, 2019) puts the springs at the head of West Cherry Creek 'just north and south of Highway 105 and a half-mile west of Highway 83'. Highway 105 ends at 83 where Walker Road begins, so the 'Walker Road and 83' and '105 and 83' placings in later accounts are the same crossing.
Wikipedia's coordinates; approximate, and still to be confirmed.
Sources
Sources are named in the text above. Numbers such as S-0080 refer to our source list. Most newspaper quotations were read in the Colorado Historic Newspapers Collection. Long quotations from recent books are shortened here.