St. Martins Therme & Lodge, Spa resort and architectural complex in Frauenkirchen, Austria

St. Martins Therme & Lodge is a thermal bath resort in Burgenland, Austria's easternmost region. The complex combines indoor and outdoor thermal pools with guest rooms, spa areas, and dining spaces all under one roof or within the same grounds.

In the 1990s, stagnating overnight stays around Lake Neusiedl prompted politicians and tourism managers to plan a thermal bath east of the lake. In 2003 the commissioned Vamed presented a positive feasibility study; in 2005 the decision fell on Frauenkirchen, and test drillings in a disused gravel pit a few kilometres south of the town found thermal water. The 13 Seewinkel municipalities, the Athena Burgenland Beteiligungen AG and the WiBAG founded the Seewinkel Therme Besitzgesellschaft m.b.H. in Eisenstadt to secure financing; project costs were 83.2 million euros.

The complex includes a Vinothek and several restaurants and bars, and it runs a "Star Club" partnership with tourism businesses of the Seewinkel. Guided excursions into the neighbouring national park are offered, and there are dedicated programmes for cyclists and for pilgrims. The thermal library is another feature of the house.

The site lies just south of Frauenkirchen, bordering the nature reserve on its south and west sides but outside it. The thermal water is pumped from 860 m at 43 °C and fed into five indoor and six outdoor pools held at 30 to 35 °C. Guided excursions into the nearby national park and a bike rental are offered, and the complex includes a running park.

The site borders the national park to the south and west but lies just outside it, a siting choice that eased building permits while keeping construction and operation low-impact. The thermal water itself is pumped from 860 m deep at 43 °C, six litres per second, and sold to the baths by two municipal companies that use the revenue to repay the project loans.