question: To prevent high water pressures at lower elevations what were built on many of the city 's buildings ?
answer: wooden roof-mounted water towers
turker_answer: To prevent high water pressures at lower elevations , wooden roof-mounted water towers were built on many of the city 's buildings .
rule-based: To prevent high water pressures at lower elevations wooden roof-mounted water towers were built on many of the city 's buildings .