Panorama stitch
Panorama stitching joins several overlapping photos into one wide or tall image. That way you capture a sweeping landscape or a tall facade with more resolution and angle of view than a single shot allows. The software aligns the photos automatically and blends the transitions.
Shoot a series with plenty of overlap (about a third per photo) and keep exposure and white balance the same for the cleanest stitch. In Lightroom you select the series and choose merge to panorama; the 'Boundary Warp' option fills in empty edges so you crop less. The result is a DNG you simply edit further. A tripod with a panorama head helps, but handheld often works surprisingly well.
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The presets on this site set these adjustments up for you as a starting point, which you then fine-tune to taste.