The present technology is generally directed to horizontal heat recovery coke ovens having monolith crowns. In some embodiments, an HHR coke oven includes a monolith crown that spans the width of the oven between opposing oven sidewalls. The monolith expands upon heating and contracts upon cooling as a single structure. In further embodiments, the crown comprises a thermally volume-stable material. In various embodiments, the monolith and thermally-volume-stable features can be used in combination or alone. These designs can allow the oven to be turned down below traditionally feasible temperatures while maintaining the structural integrity of the crown.