St. Stephen's Tower is a name which is often ascribed to The Clock Tower at the Palace of Westminster in London, which houses the 13-ton bell Big Ben, though this name is not used by staff at the Palace of Westminster itself.
The name may have come from St. Stephen's Hall, the western wing of the Palace of Westminster, which is the entrance used by visitors wishing to view the proceedings of the Houses of Parliament, and British subjects wishing to lobby their MPs.