Russia is famous for enormous amount of different achievements in different spheres of science, which are admired by people from all over the world. We can be proud of our country for inventions and discoveries that were made by its people, without which the subsequent development of humanity will not be possible. The Russian Federation is only 20 years old. But if we mean Russia as a country with a long great history including USSR and the Russian Empire it will take days to name all achievements.
But I would like to mention the most remarkable achievements of several centuries.
The first one is associated with the XIX century. In 1896 Dmitri Ivanovich Mendeleev created the Periodic System of elements and formulated the periodic law. There is no doubt that this achievement had made a great revolution in the world of chemistry. Though the structure of atom was explored only in the xx century, Dmitriy Ivanovich placed the elements according to their atomic weight predicting the complex structure of atom. What is more, this achievement gave opportunity to the development of physics, biology and other disciplines.
A lot of achievements were made in the USSR. During the rule of Lenin, the Second World War, the arm race drive the soviet science and technology contributed a lot to the development of the country and the world science. In my opinion, the most remarkable achievement that was made during the soviet period is the assault rifle of Kalashnikov (AK-47). This legendary weapon has no equal one in the world. In addition to it, AK is painted on national flags and state emblems of several African countries. Moreover, it was the only weapon in fights for independence of 63 African countries.
All in all, remarkable achievements of the world scale that could make the revolution in the world of science and technology were not made in Russia as in other countries. On the other hand, Russian scientists take part in international scientific projects; they work out projects in nanotechnologies and reach excellent results.
For example, Geim and Novoselov invented the graphene. Perelman proved Poincare conjecture.
From my point of view, the remarkable achievement is that there are still people who work and make discoveries and explorations not for money and awards but from the sense of duty and from a great love to Motherland and from desires to make our country and life in it better.