The huts of Ahch-To exist here on Earth.
THE STAR WARS SERIES HAS famously used exotic real-world filming locations as stand-ins for its alien planets. Scenes depicting Luke Skywalker’s home planet of Tatooine were filmed in Tunisia (in the region actually called Tataouine), the Battle of Hoth took place on Norway’s glaciers, and Endor’s forest moon was portrayed by the redwood groves of Northern California. In The Last Jedi, Luke Skywalker’s hermitage on Ahch-To was filmed mostly on the island of Skellig Michael, west of the Iveragh Peninsula in County Kerry, Ireland. In this case, the producers didn’t just use the island’s striking natural beauty, but also adapted the otherworldly structures built by its former inhabitants.
The ancient Jedi shelter where Luke Skywalker resides is a very terrestrial building type called a clochán, a primitive stone dwelling that can still be found on Skellig Michael.