A rare "Kastenzehner", an early series class 110 locomotive with the box-shaped front, in contrast to the more aerodynamic "BŁgelfalte"
cab style. Seen here at Cologne Central, pulling an InterCity replacement train from Bonn to Hamm.
This specimen was built in 1958 by Henschel, in continued service for over half a century by now! That's what I call well made and long lasting! Try finding a bus, ship or plane this old in the developed world that's still in use... Not as preserved unit for nostalgia runs, fueled by money from enthusiasts, but in proper service, even with a scrap-happy company like DB.
And yes, that gent to our right took a photo of it as well.