Gingerbread City

Here you can find:

Player Sprinkles

????? 9,999 sprinkles

The following locations are not available until their city improvements are enacted:

Notes

Using the December 2016 Item-of-the-Month will permanently open up the Gingerbread City for you to access. counterfeit city will give you 1 day access when used. It consists of 3 zones and a leader board for most sprinkles found that day.
First place on the Top Citizens leaderboard receives My Life of Crime, a Memoir.
Attempting to enter the city or any of its sub-zones when you don't have access (for example, via the "Last Adventure" link when you used a counterfeit city the day before) gives the message:

That's not a real place.

Transcendent Olfaction cannot be used in any zone here. Attempting to use it gives the message:

It's no use. Everything here just smells like gingerbread.

Gallapagosian Mating Call cannot be used in any zone here. Attempting to use it gives the message:

You make the mating call, but it's all weird and echoey in here, so it doesn't work.

After you have used your daily allotment of adventures (15-30), the next adventure will be Infrastructure Failure.

Attempts to continue adventuring thereafter on the same day give only the message: "The gingerbread city has collapsed."
The "Infrastructure Failure" adventure doesn't appear in the Gingerbread Sewers (presumably because the area is underground, where you can't see the collapse), so you will instead get one extra adventure there. The city still collapses and access is still cut off after this.