A complete set of hipposandals, early Roman horseshoes, were unearthed in Vindolanda, an archaeological site in Northern England, according to the BBC.

Vindolanda was the site of nine Roman forts during the Roman occupation of Britain that lasted between 400 and 500 years.

The hipposandals are more like actual shoes, as they were not nailed to the horse's hooves as modern horseshoes are. 

The find is especially rare because of the shoes’ good condition.

“Every time new Roman arrivals came, they covered over the remains from the last fort with clay and turf to make solid foundations for their fort,” says Barbara Birley, Vindolanda’s curator. “This means things were well preserved. One of the hipposandals has a hairline fracture so the set may have been thrown in the ditch because one was damaged.”

Because the forts were built upon each other using clay, oxygen was kept out making the site anaerobic. Without oxygen, iron can't rust, which explains why the shoes were in such good condition. 

Birley notes that the shoes are so well-preserved that you can even see the tread to stop horses from slipping.

Alex Meyer, a Roman historian and classical studies professor, told phys.org that it was "very odd" that all four sandals were found together. He says that they could have been deliberately buried as a memorial to a beloved horse. 

Meyer says the find also gives historians insight into what types of horses would use hipposandals and what conditions they were used in. 

"Normally, people will argue that they were used for draft animals; I'm not sure if there were draft animals at Vindolanda but it seems likely that it was cavalry that used hipposandals, too," he says. "This shows that the use of hipposandals is not just isolated to rocky terrain in the mountains where horses' feet would have to be protected, but in Vindolanda, where there is little rock and lots of grass fields, there is still a use for hipposandals."

The hipposandals are estimated to be from 140 A.D. to 180 A.D. They will be going on display in the Roman Army Museum in February 2019.