The Potomac River has served as Washington's commercial artery since 1751, when Georgetown's tobacco wharf made it the young colony's busiest inland port. By the early nineteenth century, barges laden with flour and grain navigated the same channel modern tour vessels follow, threading between Maryland's wooded bluffs and the District's emerging federal quarter. Today's Georgetown waterfront retains fragments of that mercantile past — cast-iron mooring posts, limestone warehouse foundations, the 1828 Customs House — but the working harbor has yielded to promenades and glassed dining pavilions where passengers board for Potomac River sightseeing. DC boat tours Georgetown departures trace a route planners envisioned when Pierre L'Enfant chose this tidal basin for the capital. The river frames the National Mall from an angle no street affords: the Lincoln Memorial's columns rise directly from the bank, Kennedy Center's horizontal mass anchors the northern shore, and the Washington Monument becomes a surveyor's marker orienting the entire grid. Evening cruises catch the monuments under floodlight, their reflections elongating across the current as planes descend toward Reagan National's parallel runway. The waterfront boarding zone at 3100 K Street NW occupies the site of the old Union Tavern wharf, where nineteenth-century steamboats unloaded passengers arriving from Alexandria and Mount Vernon. Modern vessels range from open-air sightseeing craft to enclosed dining salons with panoramic windows. Narrated cruises identify Theodore Roosevelt Island's wooded outline, the gothic spires of Georgetown University above the canal lock, and the Key Bridge's five limestone arches — the District's oldest span still carrying traffic. Dinner sailings pair white-tablecloth service with a southbound route past the Tidal Basin, where cherry trees fringe the Jefferson Memorial's dome and the Potomac begins its slow bend toward the Chesapeake.