Eagle 6.6.0 Professional is no longer available for free download from the official Autodesk website, as it has been replaced by Autodesk Eagle. However, you can still download Eagle 6.6.0 Professional for free from other sources:

Before downloading and installing Eagle 6.6.0 Professional, ensure that your system meets the minimum requirements:

It runs smoothly on older hardware and legacy Windows operating systems (like Windows 7 and 8).

features—like unlimited board area and 16 signal layers—require a paid subscription. Any site offering a "free professional download" is likely distributing unauthorized and potentially harmful software. 2. The Move to Autodesk Fusion