Leonid was a sociable boy and very quickly became friends with his peers, children of the actors who lived nearby. In his school years his friends were Misha Derzhavin, Shura Shirvindt, Slava Shalevitch, Mitya Dorliak, Natasha Zhuravleva. He shared the same apartment with the real beauty Valya Malyavina. In the course of time, they all became very famous actors.

Leonid studied in one of the Arbat schools and graduated with the gold medal. At first he wanted to go to «Shchuka», but life made some adjustments, and he, not without difficulty, entered one of the technical Universities of Moscow and graduated with honors. While studying at the University he actively participated in amateur performances, wrote lyrics for the student parties and «wits and humour» competitions.

After graduation, he worked as a designer, researcher, invented a lot, became one of the firsts in the country to introduce the automatic design system (CAD).

He defended his thesis successfully, combined the main work with teaching at various Universities in Moscow. Since then he has written and published more than 70 scientific works – author's certificates, articles, brochures, books (including several textbooks). All these are technical literature items.

But since school years Leonid Niessmann has aspired after fiction. And not only as a reader. Ever since he has been writing poetry and prose, participating in the creation of various performances, composing songs and patters, making translations from German and English.

Having moved to Germany, Leonid does not break ties with Russia, participates in the development and implementation of a number of successful joint

Russian-German projects. He has received the degree of Doctor of Technical Science and the title of Professor. He is actively involved in the work of the International Council of Russian Compatriots, being elected a member of its Presidium.

The circle of his friends and acquaintances is wide and diverse. Among them there are famous Russian compatriots – count Pyotr Sheremetyev, Prince Nikita Lobanov-Rostovsky, a well-known researcher of the Arctic and Antarctic, an outstanding Russian scientist-oceanographer Artur Chilingarov, one of the top-rank chess-players in the world Levon Aronian, distinguished cultural figures – Zurab Tsereteli, Arkady Inin and Leonid and Alexander Kanevsky, Nadezhda Babkina, Veronica Borovik-Khilchevsky, Roxana Babayan. Since Institute times Leonid has been friends with Yuri Luzhkov.

Life gave him the happiness of being acquainted and keeping company with now deceased outstanding representatives of national culture – a great poet and translator Samuil Marshak, the king of tango Oscar Strok, a famous film Director Grigory Chukhrai, wonderful actors Vladimir Zeldin and Semyon Farada, the legendary journalist Artyom Borovik, the master of the Russian art of singing Josiph Kobzon, the popular singers Eduard Khil and Valentina Tolkunova and also Alexander Glezer -a writer, poet, translator, journalist, publisher, collector of unofficial Russian art, one of the organizers of the «Bulldozer exhibition» in Moscow (1974).

In 2009, his book «My Friends Are My Wealth» came out. Later he wrote and published several more of his books.

In 2018 Leonid Niessmann's book «Russian Language. Difficulties, Secrets, Subtleties and Not Only…» was published. Written in vibrant, colorful language, it is cheerful, easy and at the same time informative and educational. The keynote of the whole book is the thought that «great, powerful, truthful and free» language for the Russian people is not only «support and comfort in the days of doubt and painful thoughts», but also an ever-living source of enjoyment in everyday life.