The workshop venue is at the Main building of the University of Helsinki. It is located at Fabianinkatu 33, see map here.
The participants will be staying at Hotel Arthur, located very close to both the Main building (about 500 m) and the Central Railway Station (about 500 m). It is the easiest when you are in the Station-building turn left and leave the building from the left entrance. Cross the square ‘Rautatientori’ in front of you leftward and take the street Vilhonkatu. This is a slight uphill-climbing but your hotel will be the on second street to the left, Vuorikatu. Please see a map here. You have accommodation booked by your name. Mention also that you are a guest of the University of Helsinki.
If you arrive by plane, the easiest way to reach the centre of Helsinki is to take a train from the Helsinki-Vantaa airport. Choose the train ‘P’ which is the shortest way to get to Helsinki via Tikkurila. Trains leave about every 10 min and it is about 25 min to reach the Central Railway Station (called ‘Rautatientori’). You can purchase tickets either on arrival from the vending machines (called ‘VR-automaatti’) or beforehand from the website of the Railway Company here.
It is also possible to take a bus, which will take about 50 min and also arrives at the Central Railway Station. A taxi from the airport to the hotel will take about 30 min and cost around 45-50 EUR.
You can find more information about airport transportation here.