With an impressive facade that combines Moorish, Gothic and Romanesque elements, the first grand synagogue on the Lower East Side is now surrounded by dumpling shops and Chinese herb stores, but rewind about a century and you’d find delis and mikvot (ritual bathhouses). For its first 50 years, the 1887 synagogue had a congregation of thousands and doubled as a mutual-aid society for new arrivals in need of financial assistance, health care and employment. But as Jews left the area and the congregation dwindled, the building fell into disrepair. A recently completed 20-year, $18.5 million face-lift has restored the splendor of the soaring main sanctuary, which features hand-stenciled walls and gorgeous stained glass: an original rose window and a new design by artist Kiki Smith and architect Deborah Gans. Downstairs, touch-screen displays highlight the synagogue’s architecture, aspects of worship and local history.