The Taynitskaya Tower is a round tower of the Nizhny Novgorod Kremlin. It is located in the upper part between the Koromyslova and Severnaya towers. It differs from the other round towers (except for the Chasovaya) by having a watchtower on the spire, like the Chasovaya and Nikolskaya towers.

The structure gets its name from the "secret passage" to the Pochayna River, dug under the fortress walls. In case of a prolonged siege of the Nizhny Novgorod Kremlin, one could exit to the river through the underground passage and stock up on water. In the 19th century, during earthworks for the arrangement of the Zelensky descent, this hiding place was filled in, and the underground stream was enclosed in a wooden pipe collector for water drainage. According to legend, near the Kremlin hill, at the source of the Pochayna, lies a stone boulder, and if it moves from its place, the small river, breaking free, will rush in wide streams and wash the city off the face of the earth. The tower itself also concealed destructive power: gunpowder was stored in its walls, and nearby, in a ravine, a gunpowder factory — the Zeleny Dvor — was built. The factory gave rise to the tower’s second name — "on the Zelen." The tower’s third name — Mironositskaya — is due to its proximity to the Church of the Holy Myrrh-Bearing Women. Like all the round towers of the Nizhny Novgorod Kremlin, the Taynitskaya has three tiers with loopholes equipped with combat chambers, and one tier with battlements.

In the 17th century, one copper hand cannon was installed on the Taynitskaya Tower, and in 1785-1790 the structure was converted into a food warehouse by order of the Nizhny Novgorod governor Rebinder. From 1826 to 1887, the tower housed a battalion armory intended for storing military equipment and weapons. Later, the fortification was given over to the archive of the Nizhny Novgorod voivode. During the Great Patriotic War, anti-aircraft guns were installed on the site of the demolished spire to protect the city from air raids by the German army. During restoration in the 1960s, the spire roof was restored.

In 2019, after roof repairs, installation of flooring and railings, the observation deck of the tower’s topmost tier was opened to visitors for the first time, where previously even museum-reserve staff were not allowed.

Sources:

https://ru.wikipedia.org/wiki/Тайницкая_башня_(Нижний_Новгород)