Donaldsonville's compact downtown has a run of well-preserved 19th-century commercial buildings along Railroad Avenue and the surrounding blocks. The town was prosperous enough in the antebellum era to serve briefly as the Louisiana state capital (1830–1831), and its architecture reflects that moment of ambition. It never became a large city, which is why so much survived. A short walk along the main street gives a good sense of what a prosperous Mississippi River trading town looked like before the Civil War rewrote the region's economy. The Confederate Memorial Museum and the Ascension Parish Courthouse are the most prominent landmarks; the scale is human and nothing requires more than an hour.