From Ossie McGennie in the Facebook New York’s Railroads, Subways & Trolleys Past & Present group (hence the watermark) comes this extraordinary glimpse into the past at the 138th Street/Grand Concourse station, which is under renovation with its exterior tilework temporarily stripped away, revealing what’s underneath. I was walking around Mott Haven just last week (on 11/16/19) and didn’t know this was there!
As you can see the station’s original tilework signs, with serif lettering, have been revealed at least temporarily. At least one aspect of the old tilework has never been covered over: the mosaic “MH”s in the ceiling mosaic bands, which of course stand for Mott Haven. You can see them on this NYC Subways page.
I’d say the exposed mosaics will only be visible for a few days or weeks. Who knows, the MTA may choose to restore them, but their standard practice is to stick with the uniform black and white signs used in every other station.