Good that you ask, because it seems it would have looked different. According to Greek Trophy Monuments, by Jutta Stroszeck: "The monument at Leuctra is a circular tower (3,38m in diameter) erected on three steps. The height of the tower could not be established, because there were not enough original stones. It was therefore restored in proportion. It is crowned by a Doric frieze, followed by a frieze of nine large round shields and a circular balustrade. Excavations carried out in the area brought to light some scattered conglomerate blocks, but no foundations in situ. So we have no information on whether or not it stood within a defining space. The interior of the monument is hollow, without any doubt for the reception of the [foundation for the] bronze trophy,' as Orlandos remarked. The bronze tropaion mentioned in the texts and shown on coins of the Boeotian Koinon must therefore have once stood on a pillar-like base in the center of the monument, rising high above the balustrade. The form of this monument is distinctive, the ground plan can be reconstructed as a round tower with a massive central base carrying the tropaion. Few analogies are known in architecture, and yet it does not seem likely that the monument at Leuctra was an invention for that occasion. It rather must have stood in line with an older tradition, the type and layout being developed much earlier. That ancient art was rather conservative with regard to the use of specific architectural types, especially in combination with cult buildings, can be deduced by comparing the main features of the two colossal Roman trophies that are preserved today: both the trophies from La Turbie and Adamklissi have a cylindrical central tower set on top of a quadrangular substructure. Each is crowned by a central pillar carrying the anthropomorphic stone trophy". Here drawings from the book: