We study the star-forming regions in the spiral galaxy NGC 4321 (M100). We take advantage of the spatial resolution (2.5-arcsec full width at half-maximum) of the Swift/Ultraviolet/Optical Telescope camera and the availability of three ultraviolet (UV) passbands in the region 1600<{lambda}<3000{AA}, in combination with optical and infrared (IR) imaging from Sloan Digital Sky Survey, KPNO/H{alpha} and Spitzer/IRAC, to obtain a catalogue of 787 star-forming regions out to three disc scalelengths. We use a large volume of star formation histories, combined with stellar population synthesis, to determine the properties of the young stellar component and its relationship with the spiral arms.