The remoteness of the site, the weather, the supply and cost of materials and labor, the cost and time for building permits, and the selection of materials used can all affect the cost of your castle. For 2023, new castle construction costs range from $525/sq ft to $700/sq ft for a complete finished castle.

Building a true, stone-fortified castle today is a massive financial undertaking that can cost anywhere from $10 million to well over $100 million, depending on the scale, materials, and level of historical authenticity. Unlike modern homes built with wood frames and drywall, a castle requires massive amounts of stone masonry, specialized engineering to support the weight of the walls, and often custom-crafted elements like arched windows, ironwork, and heavy timber framing. A "budget" version—essentially a large luxury mansion styled to look like a castle—might sit at the lower end of that spectrum, but a structure built with traditional methods, such as Guédelon Castle in France (a modern project using 13th-century techniques), requires decades of labor and immense funding. Land costs, modern building codes (which require plumbing, electricity, and HVAC to be hidden within thick walls), and the scarcity of skilled stonemasons further drive up the price. If you were to replicate a mid-sized medieval fortress with modern luxury interiors, you are looking at a minimum of $500 to $1,000 per square foot, making it one of the most expensive types of residential construction possible in the modern era.