The Small Isles, a gorgeous archipelago in Scotland’s Inner Hebrides, are protected as part of a National Scenic Area. But it turns out the sparsely populated islands are also now a high-tech landmark. The islands of Canna and Sanday, which are only separated by a tidal channel, are now the most minutely mapped islands in the world reports the BBC, and the imaging has unlocked thousands of years of archaeology.

Last November, the conservation charity National Trust for Scotland, which administers the islands, hired the Glasgow-based mapping firm GeoGeo to conduct a detailed drone survey of the islands to precisely locate archaeological features. Over the course of five days, a state-of-the-art fixed wing drone flew a total of about 250 miles, collecting 4,000 ultra-high-resolution images and 420 million data points. The team then used a proprietary super computer to analyze the data, creating an incredibly detailed 3-D map of the connected islands. “This not only shows detailed topography and vegetation at a game-changing three centimeters [1.18 inch] resolution but, with over 420 million data points, is currently the world’s largest complete island dataset captured by drone,” Paul Georgie, founder and lead geospatial technologist for GeoGeo says in a press release.

The maps are already revealing the past history of the island, showing previously unseen remnants of “rig and furrow” agriculture dating back to the Bronze Age. The data reveals that at its peak in the 1800s, agriculture on the island could have supported up to 400 people.

“The detail is simply astounding – aerial surveys for archaeology have been around since the end of World War Two but this new technology takes everything into a completely new realm, being considerably more detailed, affordable and flexible,” Derek Aleaxander, head of archaeology at the National Trust for Scotland, says in the release.

Today, though a handful of people still live on the islands, agriculture has given way to a colony of about 20,000 seabirds, which the Trust worried might be disturbed by the drone. They also prepared for the drone to be attacked by the golden eagles and white-tailed sea eagles in the area. Though the pilots were ready with a barrel roll in case of ambush, luckily there were no bird-drone incidents.

The data is now being used to update the archaeological inventory of the islands and to plan future digs in the area.

While the new 3-D map might be one of the more impressive feats of drone archaeology, it’s far from the only example, and will likely be eclipsed in the near future. In recent years, researchers have begun flying drones over cultural sites all over the world, getting perspectives and measurements they just can’t see by digging on their hands and knees. Michael Casey at the AP reports that thermal imaging cameras and other mapping tools can see feet underground and uncover things like buried structures or foundations that would have taken months of digging to reveal previously.

In 2016, drone imagery helped uncover an unknown massive monument in the ancient city of Petra in southern Jordan, and just last year, drone photographers found the remnants of 4,500-year-old henges, or monumental circles, in agriculture fields in Ireland’s Boyne Valley and previously unseen geoglyphs near the Nazca Lines in Peru.

No doubt, drones have the potential to make other astounding discoveries.