Charles Follen McKim’s 1895 building on Copley Square was called a palace for the people when it opened, and it has never stopped behaving like one. Marble lions on the staircase, Sargent murals in the corridors, a courtyard out of an Italian cloister — and all of it open to anyone who walks in, no ticket, no questions.

A palace, on purpose

McKim designed the building to make ordinary people feel like scholars, and the sequence still works. You climb a marble staircase past a pair of stone lions, under murals, toward light — and the building keeps handing you reasons to slow down. Edwin Austin Abbey’s Holy Grail cycle lines one hall; John Singer Sargent’s murals, a project he worked on for decades, fill a vaulted gallery upstairs. In most cities this would be a museum with an admission desk. Here it is a library, and the front door is the only formality.

Bates Hall and the courtyard

The reading room is the postcard: a barrel-vaulted hall running the length of the building’s front, lined with long oak tables and the green-shaded lamps every photographer in Boston has shot at least once. It is softer in person than in pictures, because it is full of people actually working. Downstairs, the arcaded courtyard at the building’s center is the quietest outdoor room in Back Bay — a fountain, a covered walk, and benches where nobody will hurry you.

Seeing it right

Free art-and-architecture tours run most days — check the library’s schedule — and they earn their hour, unpacking the murals and the McKim details you would otherwise walk past. Self-guiding works too: staircase, murals, Bates Hall, courtyard, in that order. The newer Boylston Street wing next door is the working modern library — lighter, louder, full of kids — and wandering between the two is its own lesson in what a century does to the idea of a public building. Pair the visit with a Newbury Street and Copley Square stroll — Trinity Church is waiting directly across the plaza.