She was raised in a prominent family and educated abroad in France and Germany before completing training as an architect at the Pennsylvania Academy of the Fine Arts.

Her first major commission, for the design of the Woman's Building for the Cotton States and International Exposition of Atlanta, was secured in 1894, while she was apprenticed to Thomas Boyd.

[3][10][11] Her mother was a poet from Bolton, Massachusetts,[11] and her father, from Bradford County, was a prominent Pittsburgh banker, businessman, and councilman.

[11] Mercur was educated in France and in Stuttgart, Germany, where she studied art, mathematics, languages, and music, becoming fluent in French and German.

[18][19][20] After completing a six-year apprenticeship with Boyd, she opened her own architectural practice in 1896 in the Pittsburgh Westinghouse Building, where she was commissioned to design homes throughout western Pennsylvania.

[16][23][24] Mercur, who was primarily commissioned to design public buildings and private homes, advertised her architectural plans in the Sunday edition of the Pittsburgh Post.

[29][30] The couple were married in the home of Mercur's brother and services were officiated by the rector Robert Maddington Grange of the Church of the Ascension.

[29] Of her decision to work in the male-dominated field of architecture, Mercur stated in an interview with The New York World that after her father had lost his fortune and died, she did not want to be dependent on her family.

[16] The April 1898 issue of Home Monthly praised her attention to detail and noted her habit of living near the construction site to ensure she could properly supervise the building project.

[35] In 1924, Wagner published a history of the towns of Old Economy Village and Ambridge Pennsylvania for the Harmony Society's centennial celebrations.

[19] Her proposal included a plastered, two-story frame building over a finished basement of brick and iron adorned with a tin roof topped by a dome.

[42][45] Painted pale yellow and white,[45] the exterior presented a grand stair and ornamental friezes, cornices; and balustrades encircling the roof.

[36][42] Visitors to the Women's Building entered through a soaring central hall, flanked by a grand double stair, in a natural wood finish.

Mercur's design for the Marshalsea Poor Farm was a one-story brick building measuring 48 by 64 feet (15 by 20 m), trimmed in stone.

[51][52][53] Built in a Roman classical style, the structure featured buff-colored brick and stone arranged with a four-story main building flanked by two large wings framing a rear courtyard.

The west wing contained administrative offices and quarters, a reception area and parlor, the dining room, and the kitchen.