This National Historic Site comprises the Custom House, the wharves and other buildings along Derby St that are remnants of the shipping industry that once thrived along this stretch of Salem. Of the 50 wharves that once lined Salem Harbor, only three remain, the longest of which is Derby Wharf. Check the website for a schedule of guided tours of the various buildings, or download an audio walking tour of the whole area.
The most prominent building along Derby St is the Custom House, where permits and certificates were issued and, of course, taxes paid. Other buildings at the site include warehouses, the middle-class Norbonne House and the fancier Elias Hasket Derby house. If you're lucky and the ship is at dock, you can climb aboard the tall ship Friendship. All are open by guided tour only.