Taivaskero Trail in Pallas-Yllästunturi National Park is a scenic loop that offers stunning views of the surrounding landscape. The hike in summer season takes about 3,5h, but with photo stops it can take more than that. So plan a good amount of time, have snacks and water with you, wear proper outdoor clothing and please check the weather before going as it can be very windy on the top.
On the highest point you’ll find a pile of rocks with a plaque commemorating the lighting of the Olympic torch in 1952.
Hiking to the top in the winter only if you are experienced, because it can be a very dangerous place on bad weather conditions and there are places where you can expose your self to avalanches.
The hotel below is a good place to ask for details and check the weather as well.
Here's a link to a free trail map: https://www.luontoon.fi/en/trails/taivaskeron-kierros-trail-muonio-190938-en