Located in the heart of Osterville - one of Cape Cod's most desirable seaside villages along Nantucket Sound - 12 Cockachoiset, known as the iconic ''Windmill House,'' offers a distinctive blend of coastal charm and architectural character. Recognized for its unique two-story windmill adorned with seaside murals, the home features a balcony with water views and serves as a memorable focal point of this special property. The main living spaces are designed for comfort and gathering, highlighted by a generous great room with a custom fireplace that opens to a covered patio and private side yard. A well-appointed kitchen adjoins the dining room, while the first floor also includes a bedroom with attached sitting room, laundry, and multiple inviting outdoor living areas. Upstairs, the primary suite is anchored by its own fireplace, private bath, and walk-in closet. An additional sitting room with balcony access and a third bedroom complete the second level, offering flexible space for guests and relaxation. Ideally located just moments from Osterville Village, this property enjoys close proximity to boutiques, dining, and nearby beaches, while also being near some of the area's most renowned marinas, including Nauticus Marina, Crosby Yacht Yard, and Oyster Harbors Marine - offering convenient access to premier boating and waterfront amenities. The adjacent property at 30 Cockachoiset Lane is also available for sale (MLS 22601972). Together, the properties offer a rare opportunity to create a side-by-side coastal compound, with a demonstrated history of significantly strong, high-value rentals and private gatherings.