BOSTON — During the 1988 presidential campaign, Vice President George Bush famously shined a spotlight on the “open sewer” that was Boston Harbor. He blamed his opponent, Gov. Michael S. Dukakis of Massachusetts, for failing to clean it up and called the harbor, which was choked with sludge and contaminated with chemicals, the dirtiest body of water in the country.

Today the harbor is the pride of Boston, a playground for pleasure boaters and even swimmers as it glistens like a necklace, ringed by glassy towers, upscale restaurants and pricey hotels.

The transformation of the harbor from embarrassment to showcase is emblematic of the larger transformation of the city over the last quarter-century.

For most of that time, one man, Mayor Thomas M. Menino, 71, has been at the helm. Although he had nothing to do with the harbor cleanup, which was ordered by the courts, he maximized its potential by encouraging nearby development. Over the two decades of his tenure, the city’s progress became intertwined with his. He was an incrementalist who, with prodding and cunning and by exercising total control, nonetheless took advantage of national trends like the back-to-city migration and helped propel Boston forward.