The Grande Mosquee sits at the heart of Zinder's old city and makes a natural starting point for exploring the Birnin quarter. The building probably dates from the 19th century and is a fine example of Sudano-Sahelian architecture — thick mud-brick walls, protruding wooden beams, and a tower that rises above the surrounding streets.
Non-Muslims are generally not permitted inside, but the exterior and the streets around it are worth time on their own. The Birnin quarter itself is one of the best-preserved historic districts in Niger, and wandering the lanes near the mosque gives you a sense of the city as it has looked for generations.