He moved to New York City, established the firm Napoleon LeBrun & Sons and designed multiple additional churches.

[3] After six years with Walter, LeBrun left to set up his own office in 1841,[2] eventually receiving as his major commissions the Cathedral-Basilica of Sts.

[4] As a young man in his twenties, LeBrun found opportunity in the booming industrial development of the Schuylkill Valley of Pennsylvania in the 1840s.

His other early work includes the original version of Trinity Episcopal Church, Pottsville (1847), still standing though much altered by later revisions.

Although both were later extensively redesigned and expanded, the notable marble facade of the Montgomery County Courthouse remains his outward and identifying creation.

[13] In 1879, LeBrun served as the American Institute of Architects representative on the Board of Examiners of the Building Bureau of the Fire Department.