Swede Herman Carlson Levin learned luthiery in the USA and founded a US fretted instrument company called the Metropolis Musical Instrument Co. in 1891, and while at this company in 1897 he filed a patent for a double neck Guitar Mandolin instrument. However soon after this he sold up, returned to Sweden and on July 27 1900 he opened the Herman Carlson Levin Musikinstrumentfabrik, (Herman Carlson Levin Musical Instrument Factory), in Göteborg. This factory made all of the common fretted instrument, (Guitars, Banjos, Mandolins), and in the late 1920 Ukuleles were added to the catalogue.

Before WWII they had two Concert scale ukuleles, the 500, (introduced in 1930), and the 505, (introduced in 1933), both mahogany with a walnut fretboard, but the 500 had white binding. It's worth remembering that Sweden was neutral in WWII, so production continued throughout the war years, but in 1942 they were changed to spruce and birch, (probably due to difficulty getting hold of mahogany), still with the walnut fretboard though. 

In 1947 these models were replaced; the new models were Sopranos, had a new headstock design, geared tuners and went back to mahogany, with the Model 90 Kamiki, (rosewood fretboard) and the Model 95 Hula, (walnut fretboard). This range was added to in 1951 with the Model 92 Honolulu, (like the Kamiki but with no binding). Ukuleles remained in the catalogue until the 1960 edition under the Levin name but they don't appear to have made them under any of the other brands they owned like Goya or Rondo until a Goya Baritone, (but made in the US by someone else?), appeared in the 1968 catalogue. 

All Levin Ukuleles had the serial number stamped on the top of the headstock and records appear to have been kept which is why they are easy to date. Though Levin did make Tenor, Guitar and Mandolin Banjos throughout their time in production there appears to be no record of them ever making any Ukulele Banjos. 

In 1972 Martin brought the Levin company and closed down all of the facilities, though they did use the Goya name for a while including for branding Far Eastern made Soprano and Concert Ukuleles, and it's worth remembering Martin didn't make instrument for Levin, Levin made instruments for Martin prior to the takeover - they were that good!.