What is this violet wild flower growing in Serbia?

Question

I would like to know characteristics of this wild flower that I found this year in my yard.

Flowers are fairly large, several cm in diameter. The whole plant is around 50 cm high. It appeared this March, first as burgundy-tinged mound of leaves, and then grew to a plant like this.

Location is Serbia, altitude 100m.

EDIT: There were two answers, suggesting two similar and biologically related plants, Hesperis matronalis and Lunaria annua. I tried figuring out what plant is in my case (by scent, leaf habitus), but could not conclude the right ID. Let's wait for june/july, when the seed pods will be created, and ID would be of course easy. Thanks anyway for both answers! :)

EDIT 2: It is Lunaria annua. We don't need to wait for June, seed pods started growing a couple of days ago, and they are Lunaria-like as seen in this picture:

So, @Bamboo and @Giacomo where right, congratulations, but also thanks to @Jurp too, different opinions always create an interesting dialogue. :)

Answer 1

The photos are a bit foggy looking and unclear; your plant may be Hesperis, but I think it is Lunaria annua, common name honesty, though it's hard to be certain because of the mistiness of the photos. Both plants are native/endemic to the Balkans. The seeds of the latter germinate easily - these plants are usually annuals, occasionally biennial, and are valued as much for their seed heads, which look like flat, silvery white 'pennies' or coins, as they are for the flowers. They dry quite well and may be used for indoor decoration. https://en.m.wikipedia.org/wiki/Lunaria_annua

Answer 2

That appears to be Hesperis matronalis, also known as Dame's Rocket. There are two sub-species endemic to the Balkans (H. matronalis nivea and H. matronalis schurii). It's considered a weed in the US, but is long-blooming and has fragrant flowers.

UPDATE: It will be easy to tell whether the plant is Lunaria or Hesperis when it goes to seed - the pods will either be circular and flat (Lunaria) or long and narrow (Hesperis).