In the south-east corner of Old Mill Pond Park is a historical brick monument.

"This monument commemorates the location of the last resting place of Hannah Tomlinson, a daughter of Joseph and Sarah Tomlinson, who passed away on October 14, 1841, ages 30 years, 7 months and 24 days.
Joseph Tomlinson Sr., her grandfather, of Welsh origin, was born in Pennsylvania in 1748. After the American Revolution, he and his wife Hanna travelled to Upper Canada with nine children, eventually settling in Markham on Lot 29, Concession 6. His son, Joseph Tomlinson Jr., (1781-1868), established a farmstead on the banks of the Rouge River, at this location. By 1815, the land was cleared and Joseph Jr. and his second wife Sarah Vancise were able to purchase this property at Lot 5 and 6, Concession 8. Here they raised a family of ten children. Hannah (1811-1841), their second child, appears to have lived here until her death. She was buried on the family farm.
In 1817, Joseph Jr. is listed as operating a woollen mill and sawmill close to this very site.By 1825, he had prospered enough to purchase Lot 11, Concession 4 where he established a second sawmill on the Rouge River. Joseph Jr. was elected councillor of the Home District from 1842-1844 and in 1852 he became the President of the Scarborough and Markham Plank Company. In 1850, a corner of the Tomlinson farm was donated to the Methodist Church to be used as a cemetery and churchyard.
The community of Sparta sprang up around the early pioneer industries, which were established in this area.Locals also dubbed the village "Sparty Wharf" as the dam marked the head of navigation on the Rouge River. In 1867, the name of the community was changed to Box Grove, in honour of the many boxwood trees around the hamlet, when the community acquired its first post office."