We recommend using public transportation to reach us.
The Ruoholahti metro station is 750 metres walking distance. The tram number 8 stops only 200 meters away from the front door and several bus lines stop at Länsisatamankatu, also 200 meters away. See the timetables here: www.reittiopas.fi
There are some parking spaces around the HTC building and next door Kaapelitehdas that allow max 4 hours parking that charge around 2 euros per hour. On the other side of Ruoholahti bridge there are some parking places for 2 hours free of charge.
If you are staying more than 4 hours we recommend using the Ruoholahti shopping center parking hall. There are 3 entrances and exits on Ruoholahdenkatu, Länsisatamankatu and Porkkalankatu. Please read more here: http://www.europark.fi/hki-ruoholahti/