 The current northern border follows Commonwealth Avenue, and on the northeast, St. Mary's Street.When Frederick Law Olmsted designed the Emerald Necklace of parks and parkways for Boston in the 1890s, the Muddy River was integrated into the Riverway and Olmsted Park, creating parkland accessible by both Boston and Brookline residents.Throughout its history, Brookline has resisted being annexed by Boston, in particular during the Boston–Brookline annexation debate of 1873.