People have been vacationing at these Soviet-era 'sanatoriums' for nearly 100 years

With its concrete walls and imposing size, Soviet-era architecture might not seem like the best setting for relaxation.

But for nearly 100 years, people in eastern Europe have been visiting full-service health spas built during the Soviet Union's reign. These spas, known as "sanatoriums," have long served as a way for weary workers to put their feet up for the weekend.

Sanatoriums are meant to rejuvenate their visitors with everything from mud baths to body-length chambers filled with carbon dioxide gas.

Many have been torn down since their initial build, but those that remain offer a unique glimpse into the ways people pamper themselves.

Many of the sanatoriums came along toward the beginning of the 20th century, like this resort in Sochi, built in the early 1930s.

"What most appeals to me about these sanatoriums is the utopian ideals on which they were founded," journalist Maryam Omidi tells Tech Insider. "By 1922, all workers were legally entitled to two weeks off a year which they could spend at a sanatorium."

Mud baths were an early favorite in the beginning, although the technology has since gotten more advanced.