Queen's Laundry Bath House, Public bath in Yellowstone National Park, US.

The Queen's Laundry Bath House is an unfinished log structure measuring 8.16 by 19 feet (2.49 by 5.8 m) on a travertine mound at the western end of Sentinel Meadows in Yellowstone's Lower Geyser Basin. Its vee-notched walls enclose two rooms of roughly equal size, and the incomplete roof was meant to be covered with earth.

Superintendent Philetus Norris proposed the bathhouse in his 1881 annual report and began building it, but his successor Patrick H. Conger declined to finish it. In 1964 the park planned to remove the ruin, then kept it as the only surviving structure from Yellowstone's early civilian management. It was listed on the National Register of Historic Places on 25 July 2001.

The name comes from the Queen's Laundry thermal feature beside it, where water is cooler than most hot springs, so early tourists bathed there. The bath house was meant for public use, and its two rooms were to serve bathers at the spring.

The ruins stand at the western end of Sentinel Meadows, on a travertine mound built up by Queen's Laundry Spring in the Lower Geyser Basin. The log walls are vee-notched and the roof frame is incomplete, so the interior is slowly being covered by hot-spring deposits. Approach on foot and watch your footing on the uneven mound.

The bath house was begun in 1881 and may be the oldest surviving visitor structure in the National Park Service system. In 1964 the park proposed removing it entirely, but kept it as the only example of a park building from Yellowstone's early civilian management.