The mission of botanical gardens is to work towards the conservation and sustainable use of plant diversity. In the case of gardens established on the premises of former manor estates, actions are also being taken to properly manage existing natural resources, e.g., historic tree stands. This article is based on the case study of the Botanical Garden in Lublin. To assess the health condition of the trees growing in the oldest part of the park—Kościuszko Redoubt—sonic tomography examinations were performed. The article presents the practical application of a newer form of digital imaging, put to the service of assessing the health of old trees in an important public space. The Redoubt is the only work of defense architecture in Poland related to the activity of General Tadeusz Kościuszko, the hero of Poland and the United States of America. It has survived in an excellent condition, preserved without significant changes, as an earth structure with ramparts; an interior, i.e., a yard; a cannon post located on an inaccessible cliff; and a brick basement serving as a shelter for soldiers and a warehouse. The entire surroundings also survived: ravines masked with a wild green, embankments with a safe hidden access road to the Redoubt, and a shaped defense line. The Botanical Garden area is located in the Sławinek district, in the valley of the Czechówka River, and includes a fragment of it and the slope adjacent to the west, cut by three loess ravines. The Botanical Garden was established in 1965, where there was a manor farm earlier, and then in the 19th century, a spa that was destroyed during World War I and II. Good soils and a varied microclimate provide the right ecological conditions for the high biodiversity of plants. With an area of 21.15 ha, the Garden area has the character of a landscape park with the theme of a manor garden from the turn of the 18th/19th century and a spa garden. The primary purpose of the work was to investigate the effectiveness of the use of computer tools in the sustainable management of historical greenery in the Botanical Garden. Research has shown that diagnostics with the use of sound waves allow for an accurate diagnosis and quick protective measures against the tree, improving the safety of visitors to the botanical garden. Moreover, the obtained results and a historical query were used to prepare an application to recognize Redoubt as a monument.