[Spooky23]

Modern is tough because it isn’t hundreds of years ago.

Around me, The High Bridge between Bronx and Manhattan was built pre Civil War and abandoned for decades and still standing (and now is use again). The Hell Gate Bridge was built by the NY Central Railroad and will probably outlast the US.

Lots of 19th century infrastructure will be around for centuries, if you look at the the path of the Erie and Lackawanna railroad routes, many bridges and other infrastructure will be standing hundreds of years from now. Lots of interstate infrastructure will function for hundreds of years in rural areas with low traffic, well beyond their engineered lifespan.

Stone is the most durable material and structures are overbuilt. Steel is much cheaper but requires maintenance.