If you need an urban bench that doesn’t require much maintenance, the best pick is a commercial-grade bench with a powder-coated aluminum frame and recycled plastic slats. This combination handles sun, rain, dirt, and heavy public use without sanding, staining, rust treatment, or board replacement.
Skip untreated steel and standard softwood. Aluminum doesn’t rust the way ordinary steel does, and a quality powder coat keeps the surface stable for years. Recycled plastic slats won’t rot, splinter, absorb water, or need painting. If you want a wood look, choose thermally modified ash or oak with stainless steel brackets instead of regular timber. Thermally modified wood is heated until it becomes dimensionally stable and much less likely to warp or decay. It will weather to a silver-gray, but that is cosmetic rather than structural.
Look for marine-grade stainless steel fasteners, since cheap bolts fail before the bench does. Choose slats with drainage gaps so water doesn’t pool, and ask for UV-stable powder coating to avoid chalking and peeling. Rounded edges and covered anchor points also reduce cleaning and rust headaches.
For most urban locations, I would pick a 1.8-meter surface-mounted bench with an aluminum frame, recycled plastic slats, and 316 stainless hardware. It is not absolutely maintenance-free, but it is about as close as public seating gets. You may occasionally wash off bird droppings, stickers, or salt spray, but there is no annual sealing, repainting, or tightening under normal use.
In short: choose aluminum plus recycled plastic, not cheap steel-and-wood furniture. The upfront cost is higher, but it saves maintenance labor within a few years.