Waterdeep is a popular location in Dungeons & Dragons campaigns, a large and influential city in the northwest region of Faerun in the Forgotten Realms, and it bears a heavy resemblance to King's Landing from Game of Thrones. Run by the Lords of Waterdeep, the city offers players a chance to explore its vast infrastructure, venturing from the slums of the Dock Ward to the finery of the Sea Ward. It's an intricate layout, but players who are also Game of Thrones fans may notice that the map of Waterdeep bears many similarities to King's Landing.
It's quite common for geographical regions in works of fantasy to look similar. Many stories take place in what boils down to an Anglo-Saxon world, drawing inspiration from the history of Great Britain and other parts of Europe - even Game of Thrones is a loose fantasy adaptation of The War of the Roses. There are also several factors that are near universal in medieval style cities, such as having a waterfront, slum neighborhood, massive place of worship and, of course, a castle located at a place of tactical advantage. Looking at an ancient map of London would also reveal some similarities to the fantasy cities of Waterdeep and King's Landing.
While Dungeons & Dragons' Waterdeep: Dragon Heist is a recent publication from 2018, Waterdeep as a location stretches back into D&D history as part of the Forgotten Realms campaign setting. Its similarity to George R.R. Martin's Game of Thrones capital is likely more coincidence than anything else, but their common threads are numerous enough to warrant inspection.
From a purely geographical standpoint, the two crafted fantasy maps share a number of uncanny similarities. Both cities are rectangular in shape, bordered on two sides to the south by water and two sides by land. Additionally, each city's respective corners bordered by sea, the southwest for Waterdeep and southeast for King's Landing, host a mountain and castle, though Game of Thrones' Red Keep sits atop the mountain, while Dungeons & Dragons Piergeiron's Palace hides behind it. Near both of these locations is a small cove frequently used for smuggling as well.
The layouts of the two cities also bear striking similarities. Just looking at aerial views of both maps show a near-identical breakdown of structures and neighborhoods. There is an area in the western section of each location that is ancient and only used during the day, the City of the Dead in Waterdeep and King's Landing's Rhaenys Hill. They both also have major roads running from the outskirts of the city to an open-air center. Waterdeep's city center is a market, while King's Landing's is an unspecified space lined with trees. Both Dungeons & Dragons' Waterdeep and Game of Thrones' King's Landing follow the formula for a medieval city, making their close similarities arguably unavoidable - but they might also make for an enjoyable afternoon for amateur cartographers who want to wander their fictional streets and compare their many commonalities.