This landmark house of worship, built in 1887, was a center of Jewish life before suffering a decline in the congregation in the late 1920s. After WWII, the main sanctuary was closed off and services relocated to the basement. The badly deteriorated synagogue was restored following a 20-year-long, $20-million restoration that was completed in 2007, and it now shines with its original splendor – it's a real stunner. Admission includes a guided tour, which departs hourly (last one is 4pm).
In addition to the restored portion of the synagogue, there's a hall of exhibits and artifacts about the history of Jewish life on the Lower East Side, as well as special events and seminars. Note that the museum is closed on all major Jewish and national holidays.