The Fifty Francs coin is a denomination of the Swiss Franc. Given that Switzerland has four official languages, the Franc has three different names: Franken in German, franc in French and Romansh, and franco in Italian.
In regular circulation, the denomination is served by a banknote. These gold coins are non-circulating legal tender made for collectors and struck in proof grade only. They are issued in topical series, celebrating various aspects of Swiss heritage or nature. Swissmint has issued at least one every year since 2001. Initially, both sides of the coin carried a commemorative design; starting from 2004, the obverse is the same and only the reverse changes. (It is worth mentioning that some sources consider it the other way round, and call the commemorative part the obverse; however, we are going with the standard definition, which is that "obverse" is the side which specifies the issuing authority).
The edge is inscribed with the motto DOMINUS PROVIDEBIT (The Lord will provide - a quote from the Bible, Genesis 22, 8), and thirteen stars representing the original thirteen cantons of the Swiss Federation.
This coin commemorates the opening of the Gotthard Base Tunnel in Switzerland.
The Gotthard Base Tunnel (GBT; German: Gotthard-Basistunnel, French: Tunnel de base du Saint-Gothard, Italian: Galleria di base del San Gottardo, Romansh: Tunnel da basa dal Sogn Gottard) is a railway tunnel through the Alps in Switzerland. It opened on 1 June 2016 and full service began on 11 December 2016. With a route length of 57.09 kilometres, it is the world's longest railway and deepest traffic tunnel, and the first flat, low-level route through the Alps. It lies at the heart of the Gotthard axis and constitutes the third tunnel connecting the cantons of Uri and Ticino, after the Gotthard Tunnel and the Gotthard Road Tunnel.
The link consists of two single-track tunnels connecting Erstfeld (Uri) with Bodio (Ticino) and passing below Sedrun (Grisons). It is part of the New Railway Link through the Alps (NRLA) project, which also includes the Ceneri Base Tunnel further south (opened on 3 September 2020) and the Lötschberg Base Tunnel on the other main north-south axis. It is referred to as a "base tunnel" since it bypasses most of the existing Gotthard railway line, a winding mountain route opened in 1882 across the Saint-Gotthard Massif, which was operating at its capacity before the opening of the GBT. The new base tunnel establishes a direct route usable by high-speed rail and heavy freight trains.
In the centre of the reverse is a depiction of the two southern tunnel entrances to the Gotthard Base Tunnel in Bodio, with a train emerging from one of them.
Above, vertically N ߍ S indicating the South / North direction of the tunnel.
Vertically below right, next to the wall of a partially visible railway station, the name of the designer F. TRÜMPI (Fredy Trümpi).
Below left, the inscription GOTTARDO (the Italian name of the tunnel) and the year it was opened, 2016.