Landmark21 began as a straightforward task: to catalogue the open web by subject, one record at a time. The result is a directory of 830 websites organised across 22 sections, maintained according to archival principles rather than commercial rankings. Unlike algorithmic indices that sort by popularity or paid placement, Landmark21 applies a simpler standard — is the site real, does it serve a discernible purpose, and has the submitting party described it honestly? Records that pass that threshold are admitted and preserved. The catalogue is arranged by subject, not by importance. Each of the twenty-two sections covers a distinct domain of human activity, from the conveyance of goods and persons to the care of animals, the practice of medicine, and the pursuit of amusement. The archivist's role here is descriptive: to record what exists, not to declare what is best. Researchers, proprietors, and the generally curious are equally welcome. Landmark21 exists to be used — to help people find resources within a particular field, to give website owners a place in a public record, and to maintain a snapshot of the web that does not depend on the shifting priorities of larger indexing systems. New entries are accepted on a rolling basis. Submission is free, and approved listings remain in the catalogue without expiry.