Some people spend their entire lives searching for ancient treasures without ever finding anything, while others stumble on it without even looking for it at all.

And that's exactly what happened to workers in the Spanish suburb of Seville, who recently uncovered 1,300 lb (590 kg) of Roman coins while trying to install new water lines.

Dated to around the 3rd or 4th century AD, the find is one of the biggest ever discovered and, since the coins were never circulated, one of the best preserved.

According to the head of Seville's Museum of Archaeology, Ana Navarro, the coins were found inside 19 Roman amphoras - a type of jug used to transport various goods, which were imprinted with images of Constantine the Great. reports Jason Daley for Smithsonian Magazine.

"It is a unique collection and there are very few similar cases. The majority were newly minted and some of them probably were bathed in silver, not just bronze," Navarro said at a press conference. "I could not give you an economic value, because the value they really have is historical and you can't calculate that."

"What is incredible is a discovery of this size - there are 19 amphoras, all complete, and I can assure you that they can't be moved by one person alone, because they weigh so much due to the coins inside," says Navarro.

According to the AFP, the coins were likely on their way to pay civil servants working in Spain at the time, though it's not known how or why they ended up buried or lost. One thing we do know is that the coins were far too heavy for a single person to carry.

Right now, the construction project has been postponed to allow archaeologists a chance to explore the area. With any luck, they'll uncover even more treasures lost long ago.

While the discovery is incredibly fortunate, it's not the first time construction workers found themselves rooting around through historic artefacts.

Back in January, workers in Virginia found a full-blown, Revolutionary War-era ship while building a hotel. In September 2015, workers in Israel found and hid a Roman-era sarcophagus while building structures in a local neighbourhood. So if you want to find some treasure, you should probably consider a career in construction.