Takegawara Onsen is Beppu's most famous historic bathhouse, housed in a wooden building from 1879 that has been maintained in its original form. The architecture — steep roof, latticed woodwork, and a warm interior smell of timber and minerals — is a striking contrast to the modern spa facilities elsewhere in the city. It is one of the few places in Beppu offering a suna-yu (sand bath): you are buried up to the neck in naturally heated black sand that draws out impurities and relaxes muscles in a way that conventional hot water bathing does not.
The sand bath requires prior arrangements and takes about 15 minutes; regular hot spring bathing in the conventional pools is available without booking. The building is listed as a cultural property. Prices are very low by Japanese standards, and the experience is a more authentic and less commercial version of the onsen circuit than most of Beppu's tourist facilities.