The Trinity Tower, located on the western side of the Kremlin, is a passage tower with a shooting gallery. It was built between 1495 and 1499 by architect Alevis Frazin, completing the fortifications along the Neglinnaya River, now the Alexander Garden. In 1516, a stone Trinity Bridge was constructed from the tower across the river, followed by the Kutafya Tower. In the 16th and 17th centuries, the Trinity Gates were the second most important after the Spassky Gates, providing access to the Kremlin for the residences of the patriarch, tsarinas, and princesses.

In the late 17th century, the tower was topped with a high tent and received architectural decor similar to that of the Spasskaya Tower, as well as clockworks that were not restored after the fire of 1812. Between 1870 and 1895, when the archive of the Imperial Court Ministry was moved to the tower, it was reconstructed, and many ancient elements were lost. In the 19th century, after the Neglinnaya River was enclosed in a pipe, the white stone ramp to the Kutafya Tower was replaced with a brick one. A new Trinity Bridge was built in 1901.

The tower has six floors and deep two-story basements, which were used for defense and served as a prison in the 16th and 17th centuries. All floors are connected by a system of stairs around the perimeter of the tower. On the second tier of the shooting gallery, there is a room with a flat ceiling. The tower is topped with a small square base, above which rises an octagonal section with an open observation area and a high tent. Decorative turrets and pinnacles on the corners of the parapets, as well as pointed arches, form the basis of the rich decor. The tower previously appeared even more ornate due to decorations on the shooting gallery.

The height of the tower to the star from the Kremlin side is 65.65 m, and with the star, it is 69.3 m. From the side of the Alexander Garden, the height of the tower reaches 76.35 m, and with the star, it is 80 m.