"Bostonians like old stuff."
— Former MBTA General Manager Thomas Glynn, in 1991.
Glynn was referring to the antique escalator at Downtown Crossing, which dated back to 1914. In the early 1990s, the still-operating escalator was coveted by the Smithsonian Institution as an antique.
It was typical of the era it was built — a narrow staircase, with wooden (as opposed to metal) threads. It was also notoriously clackety — homeless people were known to turn it off when they wanted to get some sleep.
Glynn and the MBTA did not give it up to the Smithsonian. At the time, they couldn't afford to replace it.
(It was eventually replaced during the Big Dig.)
The earliest known patent for a moving staircase comes from nearby, in Saugus. Despite having never built the machine, Nathan Ames's pre-Civil War design looks pretty modern.