Honestly, if graffiti and vandalism are your biggest concern, the answer isn’t one magic material—it’s a material plus the right finish. For most urban sites, I’d specify powder-coated galvanized steel or stainless steel with an anti-graffiti coating system. That combination gives you the best balance of strength, cleanability, and long-term cost.
Why steel? Mild steel is tough, cheap, and easy to fabricate, but it rusts if the coating gets scratched. Hot-dip galvanized steel solves that by protecting the metal even through small scratches. Stainless steel goes further: it’s hard, corrosion-resistant, and has a smooth, non-porous surface that many spray paints and markers don’t bond to as aggressively. If your budget allows, 316 stainless is the gold standard for coastal or high-abuse locations.
But the coating matters as much as the base material. Look for a two-part anti-graffiti powder coat, or a clear permanent or sacrificial anti-graffiti film over the paint. These create a slick barrier so most spray paint, marker, and sticker adhesive can be removed with a solvent wipe or pressure washer without stripping the color underneath. Sacrificial coatings dissolve during cleaning and must be reapplied, while permanent coatings are harder but can be more expensive. For a bench, I usually recommend a permanent anti-graffiti topcoat because it handles repeated cleanings.
If you’re open to non-metal options, recycled plastic or HDPE benches resist carving and never need repainting, but spray paint can still stain the surface and harsh removers may dull the finish. Concrete is heavy and nearly impossible to steal, but it’s porous unless sealed, and once spray paint soaks in, it’s a nightmare to remove. Timber—especially softwood—is the worst option here because it’s easy to carve, burn, and mark.
One more thing: design is part of the anti-vandal strategy. Avoid big, smooth, blank panels that practically invite tagging. Use slatted seats, curved edges, or perforated metal so there’s no satisfying canvas. Add tamper-resistant bolts and anchor the bench properly. No bench is 100% graffiti-proof, but a vandal resistant urban bench made from powder-coated galvanized or stainless steel with an anti-graffiti coating will be far easier to maintain—and far less attractive to vandals—than most alternatives.