Registration of a patterned flow cell may utilize fiducials comprising sets or groupings of features (e.g., sites, sample wells, nanowells) having known locations and in which the placement of the features is not in accordance with a periodic pattern or is otherwise distinguishable from the periodic pattern of sites present in non-fiducial regions of the flow cell substrate. In certain embodiments the positioning of the sites that are part of the fiducial represent a break or discontinuity in the periodic pattern of sites that are otherwise present on the surface of a patterned flow cell.