The Royal Ancient Lab Ruins are a location from The Legend of Zelda: Breath of the Wild. The ruins are found on the North Hyrule Plain west of Hyrule Castle, in the Hyrule Ridge region. It appears to be ruins of the Royal Family's local laboratory, but was destroyed during the Great Calamity.
The Hyrule Castle and the Thundra Plateau are located respectively east and west of the Royal Ancient Lab Ruins. A Lynel patrols around northeast of the ruins. Large Blue ChuChus can be encountered within the ruins and Stalkoblins can be encountered at night.
A Korok can be found within the ruins by following a flower that moves when Link touches it which will cause the Korok to reveal itself and will reward Link with a Korok Seed. Ironically, there are no signs of the ancient technology that was once studied here, indicating that it was either destroyed or removed during or after the Great Calamity (either by the researchers, treasure hunters, or forces loyal to Ganon such as monsters or Yiga Clan).
According to Purah's Diary and Robbie's Memoirs, Purah and Robbie originally conducted their Sheikah technology research here for the Royal Family before they were forced to flee during the Great Calamity which resulted in the lab's destruction. During the Age of Burning Fields, Purah set up the Hateno Ancient Tech Lab in Hateno Village and Robbie built the Akkala Ancient Tech Lab in Akkala where they continue their research to aid Link.
Before the Great Calamity, Robbie focused on researching Guardians. It is implied that Princess Zelda occasionally assisted Purah and Robbie in their research due to her interest in science and technology.