A
Serb, Lazar was born in the town of
Prizren, in the
Serbian Empire. He was a
monk with the rank of
crnorizac (; ) serving at the
Serbian Orthodox Hilandar monastery, a centre of Serbian religious and secular culture and "the first Serbian university", located on
Mount Athos. Lazar likely left Mount Athos as a result of the
Rise of the Ottoman Empire. Russian chronicles speak of Lazar, newly arrived from Serbia, inventing and building a clock on a tower in the Grand Prince's palace in
Moscow behind the Cathedral of the Annunciation at the request of
Vasily I, the
Grand Prince of Moscow (r. 1389–1425). It was the first ever spring-driven (mechanical) clock, or
striking clock, in Russia, and also the country's first public clock. The clock numbers were written in
Church Slavonic. and was regarded a technical miracle at the time. The clock tower has not survived, and its exact location is undetermined, although it is believed to have been located at or near the
Spasskaya Tower (formerly known as Frolovskaya). The clock was for a long time the only one in Moscow and Russia, and worked for more than two centuries without failure. Although the tower is gone, the illustration of the clock tower and monastery can be seen in the
Polytechnical Museum in Moscow as of 2006. ==Legacy==