   thumb|right|route of the river westbourne (highlighted in blue) shown between west end (now known as west hampstead) and the thames on a map from 1790.  the river westbourne is a small river thames tributary in london, primarily sourced from whitestone pond, hampstead heath which, notwithstanding meanders, flows approximately southward to skirt east of hyde park's serpentine lake after about , to sloane square, chelsea after about , passes centrally under the south side of royal hospital chelsea's ranelagh gardens after about , then issues into the inner london tideway.http://londonist.com/2009/11/londons_lost_rivers_from_above_the.php londonist.com: london's lost rivers from above (nov 2009) now, in common with several urbanised streams, its basin contributes to a network of storm drainage channels, with a sewer beneath its route. ==names== the river was originally called the kilburn (cye bourne â royal stream, 'bourne' being an anglo-saxon word for 'river') but has been known, at different times and in different places, as kelebourne, kilburn, bayswater, bayswater river, bayswater rivulet, serpentine river, the bourne, westburn brook, the ranelagh river, and the ranelagh sewer. it is of similar size to the fleet. ==course== rising in hampstead the river flows south through kilburn (also the name of the river at that point) running west along kilburn park road and then south along shirland road. after crossing bishops bridge road, the river continued more or less due south, between what is now craven terrace and what is now gloucester terrace. at this point, the river was known until the early nineteenth century as the bayswater rivulet and from that it gave its name to the area now known as bayswater. originally bayswater was the stretch of the stream where it crosses bayswater road, "bayards watering" in 1652 and "bayards watering place" in 1654. it is said that there is a reference to bayards watering place as early as 1380. there were a few houses at this spot in the eighteenth century and, it seems, a man called bayard used or offered it as a watering place for horses on this road (formerly uxbridge road). the river enters  hyde park at what is now the [
Rivers_of_London Subterranean_rivers_of_London Tributaries_of_the_River_Thames