The 5th Edition adventure Waterdeep: Dragon Heist is an urban style adventure based in a very large city. While the adventure itself is good and provides a lot of resources in the city, it is lacking in detail that helps the DM bring the city to life. Similarly Waterdeep: Dungeon of the Mad Mage, while a dungeon crawl, does expect that players will spend some time in the city between delves into Undermountain.
For example it gives no detail on the placement of many of the buildings it references in the adventure, leaving them up to the DM to place. This places a large burden on the DM to come up with placement for things like taverns, shops and the like on the majority of the streets in Waterdeep (of which there are a lot!).
It also gives no detail on how, or where the sewers in the city run, while having them play an important role in a variety of portions of the adventure.
Are there any resources from other editions which can help fill these gaps?