HDRI Hub has 2 free night HDRIs: HDR Night and HDR City Road Night Lights. Both carry streetlights and a dark sky rather than pure black, which keeps shadow detail visible in a render. For more variety, 21 paid night HDRIs are listed below, priced $8 to $25.
HDR Night is 6000x3000 and shows a plain night sky with a road in view. HDR City Road Night Lights is 8192x4096 and adds street lighting and reflections on the road surface. Both are free, zip-downloaded, and licensed for commercial use on one workstation. The grid below also lists the 21 paid night-tagged HDRIs in the outdoor catalog, priced $8 to $25, at resolutions from 4096x2048 up to 20000x10000.
Expose for the highlights first, then recover shadow detail, rather than trying to balance both in a single pass; this keeps bright fixtures from blowing out while architectural detail stays visible in the dark areas. A twilight or night HDRI works best as ambient fill behind foreground artificial lights, since the sky rarely goes fully black and a dim sky map avoids a crushed, noisy look in the shadows.