San Francisco

ROUGHLY two decades ago, during an earlier Internet start-up boom, many entrepreneurs and fast-typing coders and engineers set up shop in a still-gritty area of this city: South of Market Street.

The young tech crowd rented — and sometimes bought — in commercial buildings in this former warehouse area, converting them into “work-live” spaces where they operated their nascent companies and slept (once in awhile).

The boom-and-bust cycles in the tech sector move quickly, and the pace of constant reinvention and innovation is relentless.

The same is true of tastes in real estate. Today a new generation of tech dreamers is back in the South of Market area. But this time they are breathing life into a start-up wave not previously seen in San Francisco: high-rise condo living.