Sentence:  It is pleasant to swim well out into the stream of the river, and, with one's chin on a level with the wide stretch of water, take in a “trout's-eye view” of the little town, ascending in tiers of <WSD>wharfage</WSD>, trees, grey ramparts, more trees, and clustered roofs, with the old cathedral of the Trinity poised guardian-like above the crumbling walls of the Kremlin. 
Meaning of the word marked with <WSD> tags:  Wharfs collectively.