The Mousallah Complex is one of Herat's great fragments: once a mosque, madrassa, and mausoleum complex, now reduced to a few powerful remains. The most visible survivor is a single tethered minaret, with the domed tomb of Gowhar Shad nearby.
The site is melancholy and beautiful, especially if you know how much of Timurid Herat has disappeared. If the tomb is locked, ask locally whether a keeper can open it.