Pagoda's symbolism of yogi's progress to Nirvana
There are so many stupas (pagodas as you call them which are chinese versions of stupas) which architectural meanings are never recorded, they are symbols for the viewer to interpret, especially the modern ones.

Symbolism from Wikipedia

"The shape of the stupa represents the Buddha, crowned and sitting in meditation posture on a lion throne. His crown is the top of the spire; his head is the square at the spire's base; his body is the vase shape; his legs are the four steps of the lower terrace; and the base is his throne."[7]

Five purified elements

Although not described in any Tibetan text on stupa symbolism, the stupa may represent the five purified elements:[8]

The square base represents earth
The hemispherical dome/vase represents water
The conical spire represents fire
The upper lotus parasol and the crescent moon represents air
The sun and the dissolving point represents the element of space