Disclosed is a holding device for holding a hub to be installed at a nacelle. The holding device includes a carrier element with a first connection interface configured to connect the holding device to a lifting system, and a second connection interface configured to connect the device to a blade pitch bearing of the hub. Further disclosed is a pitch operating device for operating a blade pitch angle adjustment device of a hub to be mounted to a nacelle. The pitch operating device includes an actuating unit and a power interface for connecting the pitch operating device to the blade pitch angle adjustment device. Further disclosed is a hub installation system including such a holding device and such a pitch operating device. Further, a method for installing a hub at a nacelle and a method for dismounting a hub from a nacelle are described.