A German footwear brand is making history for sandals by recently being publicly listed.

According to reports, Birkenstock set a company milestone with its valuation of $8.64 billion, or $41 per share, after debuting on the New York Stock Exchange.

Another milestone is the business' longevity. The comfortable sandals patronized by celebrities and style influencers were first made 250 years ago.

Its trademark flexible insoles continue to promote healthy feet "by evenly distributing the weight and reducing pressure points and friction," CBS News reported.

Sandals, however, are ancient creations, and scientists from the Universidad de Alcalá and the Universitat Autònoma de Barcelona have found new proof of this at the Cueva de los Murciélagos of Albuñol in Granada, Spain.

According to the study on the well-preserved sandals dug up by miners in the 1900s and recently published in the journal "Science Advances," the 20 pairs of sandals found in the cave were the oldest footwear in Europe and Iberia.

"These are the earliest and widest-ranging assemblage of prehistoric footwear, both in the Iberian Peninsula and in Europe, unparalleled at other latitudes," British news service SWNS quoted Francisco Martínez Sevilla, a researcher at the Prehistory Department of UAH, as saying, Fox News reported.

Carbon-dating of the sandals and woven baskets found in the cave put their age at least 6,200 years — and possibly older, according to Fox News.

Made of wood, reed, and esparto grass, the early and middle Holocene period sandals indicated the ability of prehistoric hunter-gatherers to craft footwear, the scientists said in the study.