Temppaliaukio Church (Rock Church)- An amazing church built directly into rock, and it has perfect acoustics. A female musician was playing music while I was there, and many tourists were wandering around taking photos. I found an area on the second floor that was good for taking in the beauty, and a moment to myself.
Kamppi Chapel (Chapel of Silence)- A gorgeous structure made of three different woods, in the middle of the bustling city, where you can go to be silent and calm. They welcome all religions, and they have social workers on hand for individuals that might need to talk. In my mind, it's exactly what a spiritual place should be: a place filled with positive energy, love and compassion. There is no judgement.
Artek- A fantastic design store that also has a few art books, and small items that you can fit in a suitcase.
Academic Bookstore- A beautifully designed modern bookstore with sculptural roof lights that make for an enjoyable book searching experience. It also has a great section of stationery.
Marimekko- To see many of the original 1960's Marimekko designs in one place is a delight!
Helsinki Central railway station- It belongs in Gotham City, and is fun to look at.
Katajanokka Harbour- A lovely place to eat Vendace (tasty, tiny fried fish) from one of the many food stands while people watching and ship watching.
Ilves- A great place to get a burger with friendly service. It was my first time eating an Elk burger, and it was delicious.
Jaskan Grilli- I think you are meant to be drunk when stopping off at this food stand, and I was not; however, it was still fun to eat a giant pile of meat while standing outside in the cold. I got the Kannibal, which I think is composed of every type of bad meat you can think of, and then piled on with toppings.
Kafe Mockba- This is a perfect bar! Imagine what your favorite dive-bar in Helsinki (or Soviet-era Eastern Europe) would look like, and this bar has achieved it. The cherry on top is that they play vintage Russian records that the bartender changes with a begrudging look.
Flying Dutch- A great bar on a boat! They serve food too.
Ekberg- A relaxing cafe, from 1852, to enjoy a coffee and Korvapuusti (similar to a cinnamon roll).
Helsinki is not cheap, so I would recommend renting an apartment with Airbnb. I stayed at a lovely place in the Punavuori district, and I found it easy to get around the city.
Listen to Hanoi Rocks (Finnish rock band) to get ready for the fun time you are about to have in Finland!