This hospital used to be a so-called zendingsziekenhuis, situated at Sonder (Kolongan Atas) in the northern part of the Minahasa (Sulawesi Utara). The hospital was estabalished by the local churches in 1901.

Nowadays it is called Rumah sakit umum GMIM Siloam. The hospital is classified as a category D hospital (Registration code: 7102040) with 77 beds. Its address is: Sonder Kolongan Atas Minahasa Sulawesi Utara.
The website of the hospital is : http://www.rsugmimsiloamsonder.co.id.
From this website we copied a few statements on its history: (google translated and abbreviated):

The hospital was started in 1901 and was inaugurated in 1905. Under the auspices of the Evangelical Christian Church in Minahasa through the GMIM Medika Foundation, GMIM Siloam Sonder Hospital is the oldest hospital in Eastern Indonesia.

In 1901, starting with searching for a location and obtaining hilly land located in the village of Tounelet with an area of ​​12,669.5 M2. The work was carried out from sunset until evening, starting with logging, leveling mountainous land, it was done with the spirit of mapalus by the people at that time, and here is an excerpt from Mrs. Schoch Van Hogendorp in Maand Bericht Van Hetnederlandsch Zendeling Genootschcap:

By that year, the yard for the hospital had to be levelled, and the house itself that had been bought had to be dismantled and rebuilt elsewhere, but the timing was unfavorable because the community was facing a rice harvest that could not be postponed, but where there is a will there is a way. when the moon is bright then the work can be done at sunset. You can see the people, priests and Schoch's helpers busy working, like human ants crowding around, heavy beams being carried in rollicking from the old place to the new place, interspersed with cheerful talk and traditional songs. Old women who are unable to work provide services drinking coffee. The building materials were obtained from donations from the community or congregation with the motto "weigh the same and light and carry the same". After completing the construction of the building, on Monday, June 12, 1905, the building was inaugurated as a hospital.

The existence of the Hospital at that time was so important, making changes to the mindset of people who were born and educated in an animist and superstitious environment and nature. Sick people are wrapped in mats tightly then laid down and fumigated under the bed which is believed to drive away the spirits that cause illness, then so that the baby in the mother's womb can "come alive" then the mother should never comb her hair and cut her nails. The task at that time, apart from carrying out the function of caring for the sick, was also to give advice to think in a Christian way so that we could leave the realm of animism and superstitious beliefs. From this activity, the hospital was named Zending Genoothshap Hospital.

In 1942, during the Japanese occupation, this hospital changed its name to Byoin Minseibu Hospital. In 1945, this hospital was taken over by the Minahasa Regency Government with the name/status Sonder Assistant Hospital. Then on November 17, 1968 it was handed back to the Evangelical Christian Church in Minahasa. (GMIM). At the handover GMIM was represented by Dr. B.A. Supit from the Health Service (Department of Health) GMIM, Sonder Assistant Hospital ordained by Pdt. R.M. Luntungan, under the name Siloam Hospital, and the Acting (Acting) Head of the Hospital is Dr. Bert A. Supit.

On 24 November 1969 the leadership of Siloam Hospital GMIM Sonder was handed over to Dr. Herman G. Pioh. And through many struggles and hard work under the leadership of Dr. Herman G. Pioh, services at the hospital can be improved, accompanied by physical development that can be carried out at that time.