Thofmar Alley

Thofmar Alley winds through jumbles of buildings between Trollgate Road and Wolfsbane Way in Old Town. Like the desert it's named for, the alleyway is untouched by falling rain. No matter how severe the downpour pounding down on the surrounding buildings, the alley itself always remains completely dry. The clearly magical effect only protects the ground level of the alley, extending upwards about 8 feet. Balconies, upper portions of open stairways, and other structures that overhang or extend out into  the alley still receive as much rain as the surrounding area, but none of it reaches the dry zone at ground level. 
The effect even protects the alley form liquids poured out be people at ground level. If you pour out a bucket of water while standing in the alley, the water will simply vanish before it hits the ground. Only liquids are affected, however; if you pour out a pot of stew on the alley, the broth will vanish but any vegetables and meat in the kettle will spill to the ground normally. This aspect of the magic can actually be troublesome, since the alley's resistance to liquid means that solid waste in the alley won't simply wash away and has to be removed with a broom or shovel. 
During the rainy season, street vendors often camp out in the alley for days or weeks at a time (or rent ground-floor space from residents with alley-facing windows) in order to sell their wares to people who duck into the alley to seek shelter from the latest downpour. During this this time of year the alley is always packed with people and takes on a sort of carnival atmosphere even when the sky is clear. 
The origin and purpose of the magical effect protecting Thofmar Alley form moisture is a mystery that as far as anyone knows has been around for as long as the alley itself.