Stone buttressing, connected to this substructure, supported the south retaining wall. Thus the area was stabilised by buttressing and inserting drainage adits. Below this point, hemispherical domes experience tension horizontally, and usually require buttressing to counteract it. Ken Burns' 1994 documentary "Baseball" contained some videographic evidence buttressing Silverbush's claim. The tree has a large number of aerial stilt roots buttressing the trunk. Such buttressing was common in Roman arch construction. It also has a structural role in buttressing the west tower. The buttressing semi-domes are set in the four corners of the square under the dome. A less common feature is buttressing, especially on churches and larger houses. The trunk has smooth grey-brown bark and reaches a maximum diameter of with some buttressing. The trunk can be massive, with thick, prominent buttressing, and reach a diameter of . Round ovens require more cutting, but generally need less buttressing. Outside, the buildings tended towards mass buttressing.