Thermes Szent Lukács, Thermal bath complex in District II, Budapest, Hungary.

Thermes Szent Lukács is a thermal bath complex on the Danube bank in Felhévíz, Budapest District II, at Frankel Leó utca 25–29. Its present form dates from 1921, designed by Rezső Hikisch, and the building is eclectic inside and out after repeated rebuilding. The indoor thermal hall has a pale blue pool with wide steps and metal handrails, framed by two mottled tan stone columns with carved capitals; a balustraded wall with a carved ornament stands behind the water, with two tall grid-paned windows and a round clock between them. The yellow-plastered exterior has a tall flat-topped tower and a lower wing with round stone urns along the roofline.

The baths date back to the 12th century, when people first discovered the mineral springs in this location. The building has been renovated multiple times, blending architectural elements from different periods into its current form.

The name may derive from the German Lochbad ("hole bath"), merged with Saint Luke, patron of healing; others trace it to a medieval owner called Lukász. Until the Gellért Baths opened, this was Budapest's most modern and popular spa, drawing patients from abroad. Cured patients left marble thanksgiving plaques on the building; most were destroyed in World War II, and the survivors were set into the walls during restoration.

The complex sits on the Danube bank in Felhévíz, District II, at Frankel Leó út 25–29. The outdoor pools were converted to a filter-and-circulation system in 1999, so water is no longer drained daily into the river. In the sauna world, guests wear sauna sheets rather than swimwear. A hospital for customised treatments occupies the second floor.

Stone plaques on the walls display messages from former visitors expressing gratitude for relief and healing through the mineral waters. These personal inscriptions tell stories of people who found comfort in this place over the years.