Architectural details:

Usefulness of the Multibrush - Telling Stories with Architecture
This section came about as a result of me grappling with two hard-to-combine aspects of level editing: Overall planning versus construction of separate features. The problem is, that I can't seem to shake the impression of some fascinating architectural feature or other in favor of the overall planning required to draw lines that are sufficiently broad for an entire level. It pains me to see that most preliminary planning is quite separate from feature construction. This may seem like a contradictory statement, but nonetheless, I have found that level construction takes place on several levels that each carry a seperate motivation and structuring principle. If one focuses too much on a specific feature of a level, the proper perspective is lost, and a cool little detail is all I'm going to get. The level will never be made. If, on the other hand, I attempt to make the broad outlines of a level, it ends up as so much 'dead space' devout of well-placed details and attractive features. Details and features often seem to have been added later, as a sort of afterthought to the ambience of a particular place. Not as a specific detail that integrates the broader lines. This separatedness, also noted in Gaylesaver's construction guidelines, has stopped me dead in my tracks a good many times, staring blankly at either 'dead' space' that I refuse to retrofit for the sake of a half-assed believability factor, or a decontextualised detail with no real grounding in the level as a whole.

Stepwise Refinement Method From Detail to Place
Don't get me wrong. I have found Gaylesaver's guide to be the most informative and useful of its kind. I admire his balancing act between manageability and minimum-hassle reversibility. Yet, my approach to designing levels differs in one important way: I start with isolated features. The sight of a broken bridge in the movie 'Dark City' for example, led me to flesh out a story, theme and general mission type over the course of a single evening. So naturally, the bridge was my first construct. from 'Dark City' - click to enlargeIt has served as a focal point throughout the conceptual development of the level, storywise as well as spatially. The broken bridge symbolizes very well the main conflict of the story: Frustration with separation. By virtue of the gameplay in Thief, the traditional meaning of 'burning bridges' and leaving something behind, is not as prevalent as frustration, since this is what I assume the player will feel when he cannot cross it. Spatially, since a bridge presupposes something on it and something under it, this allows two separate spaces, one for each of the opposing themes of the conflict: Intimacy and distance.from 'Dark City' - click to enlarge
The details and features should not so much be an added in the name of believability, as it should be the medium of theme and conflict whenever plausible. As a consequence, I lend them much attention early on in the design process.This has led me to a particular way of thinking about a level at different stages of its conception.
What GayleSaver refers to as stage three of the design process is stage one in the context of my method. Every feature, such as the broken bridge, is then saved as a multibrush, and a note is made of the dimensions of its bounding box, as well as how and where it connects with the surrounding brushes. From there on, I follow GayleSaver's method, with the exception that Stage one, creation of world space, can now be worked through with an attention to how the features and details of the level will affect the layout as a whole.

Post Scriptum
Of course, if I am to start building details, I'll need a construction site to play around in. Here it is :-) :