Iron Works, Tayloe had other dealings in Prince William County, Virginia. In 1814, he purchased lots in Occoquan, and on the one that fronted Mill Street, he built the Occoquan Hotel. He served as a county postmaster for a time, and his stagecoach lines stopped in Occoquan, giving passengers a chance to disembark here. During his residence at his summer home, "Mount Airy", the mansion was enlarged, having originally been built by his father. Among his guests were men of the American Revolution. Tayloe was a member of the Federalist Party, and he was a personal friend of General George Washington. He built the Octagon House in Washington, D. C. in 1799, residing there in the winter. The Octagon was designed by Dr. William Thornton, the first architect of the U.S. Capitol. While a resident of Washington, he was elected to the board of directors at the Washington Branch of the First Bank of the United States on February 2, 1808, replacing Joseph Carleton, and later served as its president. This bank's board consisted of such men as John Van Ness, Joseph Nourse, and Benjamin Shreve Jr. of Shreve, Crump & Low. Tayloe himself chartered The Central Bank of Georgetown and Washington on March 3, 1817. On March 25, 1812, at the Davis Hotel, he founded "The Produce Bank of the Potomac" with again John Van Ness, Charles Carroll of Bellevue, Elias B. Caldwell, Tench Ringgold, C.W. Goldsborough, and John Graham (diplomat), and later added Roger C. Weightman, and James H. Blake. He was also a director at Bank of Alexandria (Alexandria, Virginia), the Bank of Metropolis and owned shares in the Washington Bridge Company, Potomac Steamboat Company, Chesapeake and Ohio Canal. He helped organize and founded St. John's Episcopal Church, Lafayette Square in 1814, served as a trustee in 1816 during its construction and upon completion served on the vestry and donated to the parish a communion service of silver, which Bishop William Meade, in his work on the old Churches of Virginia, says had been purchased by Col. Tayloe at a sale of the effects of the Lunenburg Parish Church, Farnham Church, in Richmond County, VA., to prevent its desecration for secular use. As Captain of Dragoons, he went to Western Pennsylvania, to help put down the Whiskey Rebellion. In 1799, he was appointed Major of Light Dragoons, U. S. A. by President John Adams. When General Washington