The Filaret’s Annex, directly adjoining the northern wall of the Assumption Belfry, was reconstructed simultaneously with the Belfry in 1814-1815, as they had been ruined by the French army.
Originally it was built in 1624 by architect Bazhen Ogurtsov to serve as an additional belfry for placing the giant bell. A tower-like construction with a square founding is completed with a picturesque marquee, which is richly adorned with carved white-stone details in its base. The northern side of the Annex is adjoined by a staircase tower. An architectural treatment of the façades is similar to the Bell Tower’s ones.