Helsinki in 2017 won the bid to host the 2017 Worldcon. Worldcon 75 will be held August 9-13, 2017 in Helsinki, Finland. Guests of honor are John-Henri Holmberg, Nalo Hopkinson, Johanna Sinisalo, Claire Wendling, and Walter Jon Williams. The price for an attending membership is currently €95.00.
For more, see the official Worldcon 75 website.