Though even many locals think of its fortified-looking neoclassical palazzo as a fully members-only enclave, in fact, any budding bibliophile or art aficionado can access its barrelvaulted book halls, catacomb-like card catalogs and lightfilled art galleries. All it takes to get past the brass-studded red-leather-upholstered front doors? The purchase of a day-pass membership for the enticingly wallet-friendly price of $40. One can also book a top-to-bottom docent led…

