This event is listed inactive, below is the original description:
The oldest gay bar in Rotterdam, which also has three darkrooms and a sauna. It was officially opened in 1937 at the Westzeedijk, a district that attracted the sailors who visited Rotterdam. The bar stayed open during World War II and was frequented by German soldiers. After the war the Cosmo was visited by more and more gays. After the Cosmo had moved to the Westplein the bar made it's final move to the Schiedamsesingel.
The Cosmonaut is the leather section of the bar, which is only open Friday and Saturday.