Its full name is Frankfurt am Main, distinguishing it from another Frankfurt (Frankfurt an der Oder) which lies on Germany's border with Poland.
The Rhein-Main-Verkehrsverbund (RMV) co-ordinates the public transport network around Frankfurt and the surrounding region, bringing together the services of a number of operators to form a unified network and tariff system.
Frankfurt's public transport tariff system is based on zones. A single zone covers the whole of the city of Frankfurt. At 2014 prices, a single trip costs €2.60. This permits interchange where necessary. There is also a short trip fare for journeys up to around 2km, for €1.60 while an all day ticket costs €6.60 for one person, or €9.90 for up to five people travelling together. Note that Frankfurt Airport lies outside the city zone. Higher fares apply for travel to and from the airport.
In the centre of Frankfurt, an underground metro system has replaced much of the public transport operating at street level. Nevertheless a couple of tram lines pass through the heart of the city.
A number of Frankfurt's trams carry partial or full advertising liveries.
Further tram routes skirt the city centre. Here they are mainly segregated from general traffic.
As well as the regular network of tram lines, an older tram operates at weekends and public holidays throughout the year, as the Ebbelwei Expreß. This provides an hour-long sightseeing tour, with drinks and snacks. Special fares apply.
During my visit to Frankfurt in December 2013, I noted another older tram still in use, for driver training.
The historic trams operate during special events and on private hires, including a whisky-tasting tour on the last Saturday of each month (website in German only).
Although the metro system runs through tunnels beneath the heart of Frankfurt, it emerges above ground with some on-street running beyond the city centre.
As in a number of other European cities I have visited, buses generally operate in the suburbs where they act as feeders to the tram, metro and suburban rail systems. Only a small number of bus routes reaches central Frankfurt.
Some routes use standard single-deckers with three doors.
Other routes use articulated buses, also with three doors.
In some places, the buses share the segregated lanes used by the trams.
Several of the bus routes terminate outside Frankfurt's central railway station.
The railway station is also the terminus for a number of domestic and international coach services.
Frankfurt has a cycle hire scheme, operated by DeutscheBahn (website in German only)
Double-deck buses can be seen on Frankfurt's streets. As in most European cities where I have seen them, I only observed double-deckers operating on sightseeing tours.
Tours are provided by two companies. The red vehicles are from City Sightseeing while the blue ones operate for City Tour Sightseeing.
Finally, on a few weekends each year, steam trains (website in German only) operate along a railway track on the bank of the River Main.