On the weekend there was an open house day in the Guleut Tram depot near Frankfurt central station since it was the 100 aniversary of that depot.
From left to right: O-series (in service 1969 to 2005), P-series (in service 1972 to 2016, but some are still used at replacement und reinforcement vehicles), R-series (in service since 1994, the first low-floor trams, hopefully will finally phased out whith the intoduction of the T-series, since they are a bit crap) and finally S-series (in service since 2003)