This guide covers the two regulatory systems that determine what a building may look like, and it keeps them separate because their constitutional postures are opposite. Part I explains National Register listing, the criteria, and the widely misunderstood fact that listing alone restricts almost nothing. Part II covers local designation, the certificate of appropriateness, the Secretary's Standards, economic hardship, and demolition by neglect. Part III works through the takings framework from Penn Central forward and explains why facial challenges fail and where exaction analysis creates real leverage. Part IV covers religious property and RLUIPA. Part V develops Section 106 step by step, along with Section 4(f), environmental review, archaeological protections, and repatriation obligations. Part VI covers the federal and state rehabilitation credits and the certification sequence. Part VII covers sign regulation and the content-neutrality doctrine after Reed and City of Austin. Part VIII addresses the collisions, and Part IX the practice points.