 Bernini's plan uses this horizontal axis as a major feature of his unique, spatially dynamic and highly symbolic design.The most obvious solutions were either a rectangular piazza of vast proportions so that the obelisk stood centrally and the fountain (and a matching companion) could be included, or a trapezoid piazza which fanned out from the facade of the basilica like that in front of the Palazzo Pubblico in Siena.The problems of the square plan are that the necessary width to include the fountain would entail the demolition of numerous buildings, including some of the Vatican, and would minimize the effect of the facade.