System, comprising a piece of furniture having a built-in niche which is formed in a furniture body of the furniture and has a built-in niche opening, a built-in appliance for preparing food, which is arranged in the built-in niche, and a storage device having an appliance door, having a storage space, which is arranged under the built-in appliance in the built-in niche, and having a storage mechanism, the built-in appliance arranged in the built-in niche being inaccessible by means of a furniture door of the furniture in a closed position of the furniture door, which covers the built-in niche, and being accessible in an open position of the furniture door, and the storage space being designed to accommodate the furniture door in its open position, and the storage mechanism being designed to transfer the furniture door from its closed position to its open position and from its open position to its closed position and having longitudinal guides (22, 24), which are arranged on the furniture body and/or on the built-in appliance on both sides of the furniture door, and guide rollers (26, 28), which are rotatably arranged on the furniture door and designed to correspond to the longitudinal guides (22, 24), at least two of the longitudinal guides being held on the furniture body and/or the built-in appliance so that they correspond to one another, and on opposite sides of the furniture door so that they are movable or automatically movable in such a way that the furniture door can be transferred back and forth between its closed position and its open position relative to the furniture body and the built-in appliance without collision, characterised in that four longitudinal guides (22, 24) are held on the furniture body and/or the built-in appliance and four guide rollers (26, 28) are held on the furniture door, one of the four guide rollers (26, 28) corresponding to one of the longitudinal guides (22, 24), and two of the four longitudinal guides (22, 24) being arranged on each side of the furniture door in such a way that the two longitudinal guides (22, 24) arranged on one of the two sides are arranged one above the other and spaced apart from one another, the adjustment mechanism being designed in such a way that the longitudinal guides which are held on the furniture body and/or the built-in appliance so that they are automatically movable and/or the guide rollers corresponding thereto can be moved automatically in response to a closing command and/or opening command of the furniture door applied to the adjustment mechanism, the longitudinal guides arranged at the top on the two sides being designed as the longitudinal guides which are held on the furniture body and/or the built-in appliance so that they are movable or automatically movable. a piece of furniture having a built-in niche which is formed in a furniture body of the furniture and has a built-in niche opening, a built-in appliance for preparing food, which is arranged in the built-in niche, and a storage device having an appliance door, having a storage space, which is arranged under the built-in appliance in the built-in niche, and having a storage mechanism, the built-in appliance arranged in the built-in niche being inaccessible by means of a furniture door of the furniture in a closed position of the furniture door, which covers the built-in niche, and being accessible in an open position of the furniture door, and the storage space being designed to accommodate the furniture door in its open position, and the storage mechanism being designed to transfer the furniture door from its closed position to its open position and from its open position to its closed position and having longitudinal guides (22, 24), which are arranged on the furniture body and/or on the built-in appliance on both sides of the furniture door, and guide rollers (26, 28), which are rotatably arranged on the furniture door and designed to correspond to the longitudinal guides (22, 24), at least two of the longitudinal guides being held on the furniture body and/or the built-in appliance so that they correspond to one another, and on opposite sides of the furniture door so that they are movable or automatically movable in such a way that the furniture door can be transferred back and forth between its closed position and its open position relative to the furniture body and the built-in appliance without collision, characterised in that four longitudinal guides (22, 24) are held on the furniture body and/or the built-in appliance and four guide rollers (26, 28) are held on the furniture door, one of the four guide rollers (26, 28) corresponding to one of the longitudinal guides (22, 24), and two of the four longitudinal guides (22, 24) being arranged on each side of the furniture door in such a way that the two longitudinal guides (22, 24) arranged on one of the two sides are arranged one above the other and spaced apart from one another, the adjustment mechanism being designed in such a way that the longitudinal guides which are held on the furniture body and/or the built-in appliance so that they are automatically movable and/or the guide rollers corresponding thereto can be moved automatically in response to a closing command and/or opening command of the furniture door applied to the adjustment mechanism, the longitudinal guides arranged at the top on the two sides being designed as the longitudinal guides which are held on the furniture body and/or the built-in appliance so that they are movable or automatically movable.