Washington, D.C. was not a "new city" in the sense of settling empty wilderness. The District's creation in 1790 (Residence Act) designated a federal district from land ceded by Maryland and Virginia, but the area was already inhabited.
President George Washington selected the site. French engineer Pierre Charles L'Enfant designed the baroque plan: radial avenues over a grid, grand vistas, reserved spaces for public buildings (Capitol, White House), and public squares—inspired by Versailles but adapted for republican ideals.
From 1800 (government arrival) through Civil War expansion, McMillan Plan (1901), Metro system (1976), and modern development, D.C. grew from a sparse federal village to a 700,000+ resident city—still defined by L'Enfant's vision and its unique federal status.