Castle Charm, the great fortress guarding the headwaters of the Econ River.
Castle Charm took longer than any map I have ever made (I spent nearly 40 hours on it, mostly on the waterfall and bridge). To this day it is one of my favorite maps I have ever made, even though there were a lot of mistakes made in the process. I learned more on this map than probably any until the Lockwood Arc.
Fun fact: One of my players (a co-GM for the Falleron Campaigns back when we had two parties and 14 people playing in the setting each week) sent the stock image used for the map and challenged me to make an encounter map that matched it. This could be considered my first “Request” map.