Date Masamune had his lands increased to 600,000 koku around Sendai for giving his support to Tokugawa in the Battle of Sekigahara. Sendai Castle never had a large donjon like many castles of this time period. There are various theories why and some proof that there were plans to build a large 5 story donjon though it was never carried out. Even without a large donjon it was still an impressive castle with three 3 story yagura and a great honmaru palace. Date Tadamune added the Ninomaru after he became lord of Sendai.

After the Boshin War, the honmaru was torn down. During a fire in 1882 most of the ninomaru was burned to the ground and the remaining buildings of the castle were destroyed during the bombings of WWII.

Date Masamune is by far one of the most interesting figures of his time period. Known as the "One Eyed Dragon" (he lost the use of his right eye to smallpox), he was feared by Toyotomi Hideyoshi and later became a deputy Shogun in the Tokugawa regime. Masamune actively promoted culture and industry. He built the Osaki Hachiman Shrine in Sendai and the Zuiganji Temple in Matsushima. He oraganized improvements to the rivers, forests and transformed the Osaki plain into a fertile rice field. Masamune also built a ship and dispatched his own men including Hasekura Tsunenaga to the Pope in Rome. Masamune was one of the most intelligent daimyo of his time.