Celtic Knot 1 by Frauke Smit is a free Celtic knot dingbat font built from broad, interlaced bands and solid geometric curves. Their silhouettes are compact, with sharp diagonal cuts meeting broad curves and little detail outside the main interlaced bands.
Celtic and medieval themes are the clearest match, especially for historical event graphics, fantasy game materials, and museum publishing. It can also furnish emblems for craft packaging and folk-music merchandise. The repeated over-and-under motif makes each symbol useful as an ornamental badge, not merely a piece of lettering.