When placing circular items (linework or extrusions) in Autodesk Revit products, it is easy to lock the centerpoint of the circle so that the circular item does not move. While this may seem obvious, the ability to perform this lock is slightly hidden.
To describe the process, I will be doing it inside the family editor of Revit Architecture 2012 and locking the centerpoint to intersecting reference planes.
To lock the center of a Symbolic Line circle:
- Start the Symbolic Line command from the Annotate tab -> Detail panel.
- Select the Circle option from the Draw panel and pick your desired centerpoint for the circle (intersecting reference planes for this illustration) and specify the desired radius.
- Pick the Modify button on the panel. (Note that if this is not done, then the next steps will not work for you.)
- Select the circle that you just placed to highlight it.
- Go to the Properties palette and place a checkmark next to the Center Mark Visible option. There will now be a “cross” sign visible at the centerpoint of the circle.
- Go to the Modify tab and select the Align command from the Modify panel. You can now select the vertical reference plane, then the little cross at the circle centerpoint to lock the circle to that plane.
- Repeat the Align command to lock the circle to the horizontal reference plane.
- The centerpoint of the circle will now stay locked to the intersection of the two selected reference planes.
You can also use the above method to lock the circle centerpoint to a dimension instead of using reference planes.
The steps outlined above are similar for locking the circular portion of an extrusion when in extrusion editing mode, except the Properties palette will look similar to the following when highlighting the circular sketch.
The above process is similar in earler versions of Revit Architecture, as well as Revit Structure and Revit MEP, but the location of some commands may be slightly different.
Applying Technology to Architecture 
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