The Gromovaya (Thunder) Tower is one of five 16-faceted (or so-called "round") towers of the Smolensk Fortress Wall. The fortress was erected under the guidance of the architect Fyodor Kon between the years of 1596 - 1602. The Russian Tsar Boris Godunov took part in the laying of the fortress.
The tower had various names: Kruglaya (Round), Tupinskaya (Obtuse-angled) and Gromovaya (Thunder). The height of the tower with its merlons was 22 meters. It had being made of bricks when using the technology of the half-rubble brickwork.
The socle is built of white stone. Below the merlons there are overhanging loop-holes grouped in twins. In 1976 a weathercock shaped like Gamayun, the heraldic bird of the Smolensk coat of arms, was settled at the top of the hipped roof.
The loop-holes are disposed in chess-board order. The casings of the loop-holes of the ground line of fire are carried out in the forms of rectangular frames. The rest loop-holes have the same casings added with high triangle crowns.
There are four tiers inside of the tower with gently sloping cupola vaults between them. On the socle tier (the first tier of the tower or the ground floor of the occupied building) there are five loop-holes disposed in the wide vaulted niches and an arched doorway leading to the 5,1meters long passage in the place where the tower is linked with the fortress wall.
The staircase leads from the passage to the second tier (the first floor) and to the battle platform of the tower. The second tierof the tower has four loop-holes and an arched aperture leading to the passage like the previous one. The staircase leads from it to the third tier (the second floor) which has five loop-holes. To the fourth tier leads the staircase with stairs made of bricks