On the 25th of August 1823 the Grand Ducal Ministry of Karlsruhe granted the "Rosenwirth Schnell of Bruchsal”, who was also a short-term tenant of the guest house “city of Karlsruhe” in Badenweiler, the approval for the construction of the Römerbad Hotel on the "little castle mat". The plans for the four-leaf plant with a square courtyard and single-storey entrance wing, was provided by the Freiburg district architect Christoph Arnold.
On the 11th of October 1823 Ludwig Joner was born. Joner later became the owner of the hotel Römerbad. He was the son of Johann Jacob Joner and of his third wife Anna Leiniger.
In 1824, the hotel Römerbad became the property of John Jacob Joner, whose family had immigrated to Germany from Switzerland in the 17th Century. The hotel remains in family ownership until the late 20th Century. A year later, in 1825, the first guests are received.
Already in 1846 the building was too small and had to be extended. The single-storey entrance wing was increased, allowing more space.
Bertha Herbster is born on 31st of March 1847 as the daughter of Emil and Verena Herbster, born Arzet.
From 1853-1868 Louis Joner was mayor of Badenweiler.
In 1863, the building permit was issued for a new single-storey bath house on the side of the valley.
In 1874, Louis Joner and his wife Bertha, born Herbster, took over the management of the hotel. They married on 12th of February in the same year. The couple had three children: Bertha, born on 28th of December 1874. Her sister, Alice, was born on 27th of May 1876, and her brother, Ernst Ludwig (also called Louis), on 31st of January 1880. Ernst Ludwig later took over the management of the hotel.
In winter 1880/81 the hotel was refurbished and redesigned by the renowned Swiss hotel architect Horace Edouard mayor Davinet. The courtyard was roofed and turned into an eight-sided room. As well as that, the outside of the hotel Römerbad received its present shape with its three floors and a mansard roof.
However, Louis Joner never saw the results of this refurbishment after the hotel re-opened. He died on 24th of May 1881. Consequently, his wife Bertha Joner took over the management of the hotel for the following years and re-opened the hotel on 15th of June 1881.
Between 1903 and 1906, the south-west wing of the central unit was added. It was designed by the Basle architects William and Alfred Bernoulli Romang.
Louis-Ferdinand Theodor Paul Bismarck Fellmann was born on 3rd of June 1915 in Berlin-Wilmersdorf. His future wife, Elizabeth Bertha Joner, was born on the2nd of August of the same year.
To mark the centenary of the hotel Römerbad, Bertha Joner received the honorary citizen award of the town Badenweiler on 1st of July 1924. After her death on 9th of August 1930, her son Louis Joner took over the hotel management.
On5th of December 1941, Klaus Lauer is born as the son of Elizabeth Joner and her husband Heinrich Lauer.
In 1947-1952, Louis Johner received many honorary positions in the church. He also held his post at the South Baden Tourist Board Association. The association grew and ended up having 278 members. Louis Joner was also appointed to the federal board and the advisory board of German National Tourism. Under his leadership, the hotel was also purveyor of His Royal Highness the Grand Duke of Baden.
On 30th of January 1955 Louis Joner received the honorary citizen award of Badenweiler.
Louis Johner died on 14th of April 1956 in Freiburg. With his daughter Elisabeth Joner and Louis-Ferdinand Fellmann, the management of the hotel was in the hands of the fourth generation of the family.
To allow guests to bathe during the entire year, the indoor thermal bath was built in the main building in 1971.
A special music forum was built in 1973, with the first Römerbad Music Festival led by Klaus Lauer taking place in the same year and the annually from then on.
In 1983, the hotel Römerbad became a member of the Hotel Association "Leading Hotels of the World" and was open throughout the entire year from then on.
In 1987, an extensive renovation took place where the rooms were redesigned.
Elizabeth Fellmann died on 17th of May 2001 in Staufen. Her husband, Louis-Ferdinand Fellmann, died a year earlier on 14th of September. As a result, Klaus Lauer officially took over the leadership of the hotel Römerbad.
In 2005, after being in family ownership for 180 years, the ownership is passed on to the family of Karl-Heinz Berkner. This change of ownership led to a room-renovation.
In the year 2006, the Roman cellar is opened. In addition, the hall area, restaurant and corridors were redesigned.
With the renovation of the bar in 2007, the hotel Römerbad received another modern touch.
Since summer 2008 an outside pool on the hotel grounds allows guests to swim in thermal water outside of the hotel.
On 1st of August 2009, the traditional 5-star Grand Hotel was bought by the von der Heyden Group. The Spanish company IBB Hotels took over the operational management.
On 1st of January 2011, Mr. Vladimir Saal and Mrs. Sandra Kunert took over as hotel manager and director. Since then, repositioning and new marketing strategies are introduced to the historic first-class hotel.
On 1st October 2013, the Panacée Betriebsgesellschaft mbH took over management. From that time, General Manager is Mrs. Siriya Thepcharoen. Sandra Kunert still holds the position of the hotel manager, Mr. Vladimir Saal becomes procurator. At the end of 2013 the reconstruction of the extension of the building to a Medical Center begins.
In the beginning of 2014 further renovations have started. Up to this day, 36 rooms have been renovated.