Central Tallinn and the Old Town are lovely areas for walking from one place to another. Public transportation is also available and there are several bicycle rental stations around the city.
The conference venue is the Tallinn University Conference Centre, address Narva maantee 25 (map).
You can find local public transportation information here.
For information on Tallinn bicycle rentals see here.
One of the local taxi service providers can be found here.
MyData 2017 encourages you to enjoy Helsinki by walking and cycling (try the city bikes or ask for a bike from your hotel).
The venue, Kulttuuritalo or Helsinki Hall of Culture, is situated by Linnanmäki amusement park and near Helsinki city centre. The address of the venue is Sturenkatu 4 (map).
You can find information on connections to and from the airport here.
You can find information on connections to and from the conference venue here.
You can find information on public transportation in the Helsinki region here.
For information on Helsinki city bikes, see here.
Local taxi service information can be found here.
Uber is also operational in Helsinki. See their website here.