diff --git a/docs/stylesheets/extra.css b/docs/stylesheets/extra.css
index 673b6538b..3393edbf0 100644
--- a/docs/stylesheets/extra.css
+++ b/docs/stylesheets/extra.css
@@ -32,3 +32,13 @@
 .md-nav__title .md-nav__button.md-logo svg {
   width: auto;
 }
+
+.md-version__list li:nth-last-child(1) a {
+  color: gray;
+}
+
+/* bit of a hack to stop the banner taking space when empty */
+.md-announce .md-announce__inner {
+  margin: 0;
+  padding: 0;
+}
diff --git a/hack/build-with-blog.sh b/hack/build-with-blog.sh
index b96282c63..1f844c283 100755
--- a/hack/build-with-blog.sh
+++ b/hack/build-with-blog.sh
@@ -1,53 +1,118 @@
 #!/bin/bash
 
-# Builds blog and community into the site by cloning the website repo, copying blog/community dirs in, running hugo.
-# - Results are written to site/ as normal.
-# - Run as "./hack/build-with-blog.sh serve" to run a local preview server on site/ afterwards (requires `npm install -g http-server`).
-
-# Quit on error
 set -e
-# Echo each line
 set -x
 
-# First, build the main site with mkdocs
-rm -rf site/
-mkdocs build -d site/docs
+# Builds blog and community into the site by cloning the website repo, copying blog/community dirs in, running hugo.
+# Also builds previous versions unless BUILD_VERSIONS=no.
+# - Results are written to site/ as normal.
+# - Run as "./hack/build-with-blog.sh serve" to run a local preview server on site/ afterwards (requires `npm install -g http-server`).
+#
+# PREREQS (Unless BUILD_BLOG=no is set):
+# 1. Install Hugo: https://www.docsy.dev/docs/getting-started/#install-hugo
+# 2. For Mac OSX: The script uses the `gnu` version of `sed`. To install `gnu-sed`, you use brew:
+#    1. Run `brew install gnu-sed`
+#    2. Add it to your `PATH`. For example, add the following line to your `~/.bash_profile`:
+#      `PATH="/usr/local/opt/gnu-sed/libexec/gnubin:$PATH"`
+
+# Releasing a new version:
+# 1) Make a release-NN branch as normal.
+# 2) Update VERSIONS below (on main) to include the new version.
+#    Order matters :-), Most recent first.
+VERSIONS=("0.23" "0.22" "0.21")
+# 3) For now, set branches too. (This will go away when all branches are release-NN).
+BRANCHES=("mkrelease-0.23" "mkrelease-0.22" "mkrelease-0.22")
+REPOS=("julz" "julz" "julz")
+# 4) PR the result to main.
+# 5) Party.
+
+community_branch=${COMMUNITY_BRANCH:-main}
+community_repo=${COMMUNITY_REPO:-knative}
+latest=${VERSIONS[0]}
+previous=("${VERSIONS[@]:1}")
 
-# Re-Clone
-# TODO(jz) Cache this and just do a pull/update for local dev flow.
-# Maybe also support local checkout in siblings?
 rm -rf temp
 mkdir temp
-git clone --recurse-submodules https://github.com/knative/website temp/website
-git clone https://github.com/knative/community temp/community
+rm -rf site/
 
-# Move blog files into position
-mkdir -p temp/website/content/en
-cp -r blog temp/website/content/en/
+if [ "$BUILD_VERSIONS" == "no" ]; then
+  # HEAD to /docs if we're not doing versioning.
+  mkdocs build -f mkdocs.yml -d site/docs
+else
+  # Versioning: pre-release (HEAD): docs => development/
+  mkdocs build -f mkdocs.yml -d site/development
 
-# Clone community/ in to position too
-# This is pretty weird: the base community is in docs, but then the
-# community repo is overlayed into the community/contributing subdir.
-cp -r community temp/website/content/en/
-cp -r temp/community/* temp/website/content/en/community/contributing/
-rm -r temp/website/content/en/community/contributing/elections/2021-TOC # Temp fix for markdown that confuses hugo.
+  # Latest release branch to /docs
+  git clone --depth 1 -b ${BRANCHES[0]} https://github.com/${REPOS[0]}/docs "temp/docs-$latest"
+  pushd "temp/docs-$latest"
+  KNATIVE_VERSION=$latest mkdocs build -d ../../site/docs
+  popd
 
-# Run the hugo build as normal!
+  # Previous release branches release-$version to /v$version-docs
+  versionjson=""
+  for i in "${!previous[@]}"; do
+    version=${previous[$i]}
+    versionjson+="{\"version\": \"v$version-docs\", \"title\": \"v$version\", \"aliases\": [\"\"]},"
+    git clone --depth 1 -b ${BRANCHES[$i+1]} https://github.com/${REPOS[i+1]}/docs "temp/docs-$version"
+    pushd "temp/docs-$version"
+    KNATIVE_VERSION=$version VERSION_WARNING=true mkdocs build -d "../../site/v$version-docs"
+    popd
+  done
 
-# need postcss cli in PATH
-PATH=${PATH}:${PWD}/node_modules/.bin
-pushd temp/website
-hugo
-popd
+  # Set up the version file to point to the built docs.
+  cat << EOF > site/versions.json
+  [
+    {"version": "docs", "title": "v$latest", "aliases": [""]},
+    $versionjson
+    {"version": "development", "title": "(Pre-release)", "aliases": [""]}
+  ]
+EOF
+fi
 
-# Hugo builds to public/, just copy over to site/ to match up with mkdocs
-mv temp/website/public/blog site/
-mv temp/website/public/community site/
-mv temp/website/public/css site/
-mv temp/website/public/scss site/
-mv temp/website/public/webfonts site/
-mv temp/website/public/images site/
-mv temp/website/public/js site/
+if [ -z "$SKIP_BLOG" ]; then
+  # Clone out the website and community repos for the hugo bits.
+  # TODO(jz) Cache this and just do a pull/update/use siblings for local dev flow.
+  git clone --depth 1 https://github.com/knative/website temp/website
+  pushd temp/website; git submodule update --init --recursive --depth 1; popd
+  git clone -b ${community_branch} --depth 1 https://github.com/${community_repo}/community temp/community
+
+  # Move blog files into position
+  mkdir -p temp/website/content/en
+  cp -r blog temp/website/content/en/
+
+  # Clone community/ in to position too
+  # This is pretty weird: the base community is in docs, but then the
+  # community repo is overlayed into the community/contributing subdir.
+  cp -r community temp/website/content/en/
+  cp -r temp/community/* temp/website/content/en/community/contributing/
+  rm -r temp/website/content/en/community/contributing/elections/2021-TOC # Temp fix for markdown that confuses hugo.
+
+  # See https://github.com/knative/website/blob/main/scripts/processsourcefiles.sh#L125
+  # For the reasoning behind all this.
+  echo 'Converting all links in GitHub source files to Hugo supported relative links...'
+  pushd temp/website
+  # Convert relative links to support Hugo
+  find . -type f -path '*/content/*.md' ! -name '*_index.md' ! -name '*index.md' ! -name '*README.md' \
+    ! -name '*serving-api.md' ! -name '*eventing-contrib-api.md' ! -name '*eventing-api.md' \
+    ! -name '*build-api.md' ! -name '*.git*' ! -path '*/.github/*' ! -path '*/hack/*' \
+    ! -path '*/node_modules/*' ! -path '*/test/*' ! -path '*/themes/*' ! -path '*/vendor/*' \
+    -exec sed -i '/](/ { s#(\.\.\/#(../../#g; s#(\.\/#(../#g; }' {} +
+  # Convert all relative links from README.md to index.html
+  find . -type f -path '*/content/*.md' ! -name '_index.md' \
+      -exec sed -i '/](/ { /http/ !{s#README\.md#index.html#g} }' {} +
+  # Convert all Markdown links to HTML
+  find . -type f -path '*/content/*.md' \
+      -exec sed -i '/](/ { /http/ !{s#\.md##g} }' {} +
+
+  # Run the hugo build as normal!
+  PATH=${PATH}:${PWD}/node_modules/.bin hugo
+  popd
+
+  # Hugo builds to public/, just copy over to site/ to match up with mkdocs
+  for d in blog community css scss webfonts images js; do
+    mv temp/website/public/$d site/
+  done
+fi
 
 # Home page is served from docs, so add a redirect.
 # TODO(jz) in production this should be done with a netlify 301 (or maybe just copy docs/index up with a base set).
diff --git a/mkdocs.yml b/mkdocs.yml
index fa8d8ff31..f246037bb 100644
--- a/mkdocs.yml
+++ b/mkdocs.yml
@@ -231,6 +231,7 @@ markdown_extensions:
       emoji_index: !!python/name:materialx.emoji.twemoji
       emoji_generator: !!python/name:materialx.emoji.to_svg
   - attr_list
+  - meta
   - pymdownx.superfences
   - pymdownx.tabbed
   - pymdownx.details
@@ -250,8 +251,6 @@ copyright: "Copyright © 2021 The Knative Authors"
 
 extra:
   branch: v0.23.0 # Branch to use for examples
-  # version for download links, empty or "dev" to use googlestorage nightlies.
-  # version: v0.23.0
   social:
     - icon: fontawesome/brands/twitter
       link: https://twitter.com/KnativeProject
@@ -261,5 +260,8 @@ extra:
     - icon: fontawesome/brands/slack
       link: https://slack.knative.dev
       name: Slack
+  # TODO: Replace with https://github.com/mkdocs/mkdocs/pull/2267 once mkdocs 1.2 is out.
+  version_warning: !!python/object/apply:os.getenv ["VERSION_WARNING"]
+  knative_version: !!python/object/apply:os.getenv ["KNATIVE_VERSION"]
   version:
     provider: mike
diff --git a/overrides/main.html b/overrides/main.html
new file mode 100644
index 000000000..6fa5ef26c
--- /dev/null
+++ b/overrides/main.html
@@ -0,0 +1,13 @@
+{% extends "base.html" %}
+
+{% block announce %}
+{% if config.extra.version_warning %}
+<div class="versionwarning" style="margin: .6rem auto; padding: 0 .8rem">
+  <h1 style="color: #ffcc00">You are viewing documentation for Knative version: {{ config.extra.knative_version }}</h1>
+  <p>
+  Knative {{ config.extra.knative_version }} documentation is no longer actively maintained. The version you are currently viewing is a static snapshot. For up-to-date documentation, see <a href="{{ base_url }}/../docs/">the latest version</a>.
+  </p>
+</div>
+{% endif %}
+{% endblock %}
+