You can't see it, touch it or hold it in your hand - nevertheless, time is a fascinating topic.

The Old Tretyakov Gallery this month tackles the question of the nature of time with its exhibit "The Birth of Time."

The exhibit - a joint project linking the Tretyakov Gallery, the Historical Museum, a number of museums from all over Germany, a Zurich museum and the Louvre - presents the concept of time as it is defined by art.

Featured in the exhibit are an ancient Egyptian water clock, a model of Stonehenge, sundials, antique Russian icons illustrating the Russian Church holidays and a great deal more. Of particular note are German Renaissance-era painter and engraver Albrecht D?erer's etchings of Jesus Christ, which illustrate that period's European Christian linear notion of time as beginning with the creation of the world and ending on Judgment Day. Alternately, Chinese vases on display feature a circular calendar. A special section ofthe exhibit is dedicated to the first European observatory, founded in Germany in 1560.

At the Old Tretyakov's sister gallery, the New Tretyakov, the nature of time features less directly in the theme of a new exhibit, the focus of which is a 40-year period of Russian art. "Twentieth-Century Russian Art: The 1950s-1980s" will feature over 300 paintings, 200 sculptures and 300 drawings by Russian artists of that era, which began with Nikita Krushchev's "thaw" and ended with the first years of glasnost.

The later works - some of which the gallery obtained especially for this exhibit and some of which were loaned to the gallery by the artists themselves - include those by such celebrated contemporary artists as Vyacheslav Nemukhin and Eduard Gorokhovsky.

"The Birth of Time" (Rozhdenniye Vremeni) runs until Aug. 20 at the Old Tretyakov Gallery, located at 12 Lavrushensky Pereulok. Metro Tretyakovskaya. Tel. 951-1362. 10 a.m. to 7 p.m., closed Mondays.

"Twentieth-Century Russian Art" is a permanent exhibit. It opens Saturday at the New Tretyakov Gallery, located at 10 Krymsky Val. Metro Oktyabrskaya, Park Kultury. Tel. 230-7788, 238-1378. 10 a.m. to 7 p.m., closed Mondays.

- Elena Ryumina