diff --git a/cssllc-admin-last-updated.php b/cssllc-admin-last-updated.php
new file mode 100644
index 0000000..dfcac8c
--- /dev/null
+++ b/cssllc-admin-last-updated.php
@@ -0,0 +1,307 @@
+<?php declare( strict_types=1 );
+
+class CSSLLC_Admin_Last_Updated {
+
+	const OPTION_NAME = '_cssllc_admin_last_updated';
+
+	/**
+	 * Initialize.
+	 *
+	 * @return void
+	 */
+	public static function init() : void {
+		static $once = false;
+
+		if ( ! empty( $once ) ) {
+			return;
+		}
+
+		$once = true;
+
+		new self;
+	}
+
+	/**
+	 * Construct.
+	 */
+	protected function __construct() {
+
+		add_action( 'admin_print_scripts', array( $this, 'action__admin_print_scripts' ) );
+		add_action( 'admin_print_footer_scripts', array( $this, 'action__admin_print_footer_scripts' ) );
+
+		add_action( 'update_option_blog_public', array( $this, 'save_option_timestamp' ), 10, 3 );
+		add_action( 'delete_option_blog_public', array( $this, 'save_option_timestamp' ) );
+		
+		if ( ! defined( 'WP_CLI' ) || ! WP_CLI ) {
+			return;
+		}
+		
+		WP_CLI::add_command( 'admin-last-updated clear', array( $this, 'cli__clear' ) );
+		WP_CLI::add_command( 'admin-last-updated get',   array( $this, 'cli__get' ) );
+		WP_CLI::add_command( 'admin-last-updated list',  array( $this, 'cli__list' ) );
+
+	}
+
+	/**
+	 * Update option.
+	 *
+	 * @param string $id
+	 *
+	 * @return void
+	 */
+	protected function update_timestamp( string $id ) : void {
+		$option = get_option( self::OPTION_NAME, array() );
+
+		if ( empty( $option ) ) {
+			$option = array();
+		}
+
+		$option[ $id ] = current_time( 'timestamp', true );
+
+		update_option( self::OPTION_NAME, $option, false );
+	}
+
+	/**
+	 * Print JSON object of timestamps.
+	 *
+	 * @return void
+	 */
+	protected function print_json_object() : void {
+		$option = get_option( self::OPTION_NAME, array() );
+
+		if ( empty( $option ) ) {
+			$option = array();
+		}
+
+		$option = array_map( static function( int $value ) : string {
+			return human_time_diff( $value ) . ' ago';
+		}, $option );
+
+		$option = json_encode( $option );
+		?>
+
+		<script>
+			// CSSLLC Admin Last Updated
+			window.cssllc_admin_last_updated = <?php echo $option ?>;
+		</script>
+
+		<?php
+	}
+
+	/**
+	 * Action: admin_print_scripts
+	 *
+	 * Print JSON object of timestamps.
+	 *
+	 * @uses $this->print_json_object()
+	 *
+	 * @return void
+	 */
+	public function action__admin_print_scripts() : void {
+		if ( 'admin_print_scripts' !== current_action() ) {
+			return;
+		}
+
+		$this->print_json_object();
+	}
+
+	/**
+	 * Action: admin_print_footer_scripts
+	 *
+	 * Print JavaScript to add "Last updated" text.
+	 *
+	 * @return void
+	 */
+	public function action__admin_print_footer_scripts() : void {
+		if ( 'admin_print_footer_scripts' !== current_action() ) {
+			return;
+		}
+
+		if ( 'options-reading' !== get_current_screen()->base ) {
+			return;
+		}
+		?>
+
+		<script>
+			// CSSLLC Admin Last Updated
+			( function() {
+				var data = window.cssllc_admin_last_updated;
+
+				if ( ! document.querySelector( 'tr.option-site-visibility th' ) ) {
+					return;
+				}
+				
+				if ( ! data.blog_public ) {
+					data.blog_public = 'Unknown';
+				}
+				
+				document.querySelector( 'tr.option-site-visibility th' ).innerHTML += '<br /><small style="font-weight: 400;">Last updated: ' + data.blog_public + '</small>';
+			} () );
+		</script>
+
+		<?php
+	}
+
+	/**
+	 * Action: update_option_{$option_name}
+	 *
+	 * Save timestamp on option update/delete.
+	 *
+	 * @param mixed $old_value
+	 * @param mixed $new_value
+	 * @param mixed $option_name
+	 *
+	 * @uses $this->update_timestamp()
+	 *
+	 * @action update_option_{$option_name}
+	 * @action delete_option_{$option_name}
+	 *
+	 * @return void
+	 */
+	public function save_option_timestamp( ...$args ) : void {
+
+		// Action: delete_option_{$option_name}
+		$option_name = $args[0];
+
+		// Action: update_option_{$option_name}
+		if ( 3 === count( $args ) ) {
+			$old_value   = $args[0];
+			$new_value   = $args[1];
+			$option_name = $args[2];
+
+			if ( $old_value === $new_value ) {
+				return;
+			}
+		}
+
+		$this->update_timestamp( $option_name );
+	}
+
+	/**
+	 * CLI command: admin-last-updated clear
+	 *
+	 * @param array $ids
+	 * @param array $assoc
+	 *
+	 * @return void
+	 *
+	 * @todo test
+	 */
+	public function cli__clear( array $ids, array $assoc = array() ) : void {
+		$option          = ( array ) get_option( self::OPTION_NAME, array() );
+		$count           = count( $ids ) || count( $option );
+		$count_format    = _n( '%d timestamp', '%d timestamps', $count );
+		$question_format = 'Are you sure you want to clear ' . $count_format . '?';
+		$question        = sprintf( $format, $count );
+		
+		WP_CLI::confirm( $question, $assoc );
+		
+		// Clear all timestamps.
+		if ( empty( $ids ) ) {
+			$cleared = delete_option( self::OPTION_NAME );
+			
+			if ( ! $cleared ) {
+				WP_CLI::error( sprintf( 'Unable to clear ' . $count_format, $count ) );
+			}
+			
+			WP_CLI::success( sprintf( 'Cleared ' . $count_format, $count ) );
+		}
+		
+		// Clear specified timestamps.
+		foreach ( $ids as $id ) {
+			unset( $option[ $id ] );
+			WP_CLI::debug( sprintf( 'Cleared `%s`', $id ) );
+		}
+		
+		$updated = update_option( self::OPTION_NAME, $option, false );
+		
+		if ( ! $updated ) {
+			WP_CLI::error( sprintf( 'Unable to clear ' . $count_format, $count ) );
+		}
+		
+		WP_CLI::success( sprintf( 'Cleared ' . $count_format, $count ) );
+	}
+
+	/**
+	 * CLI command: admin-last-updated get
+	 *
+	 * @param array $args
+	 * @param array $assoc
+	 *
+	 * @return void
+	 *
+	 * @todo test
+	 */
+	public function cli__get( array $args, array $assoc = array() ) : void {
+		$id = $args[0];
+		$option = ( array ) get_option( self::OPTION_NAME, array() );
+		
+		if ( 
+			   empty( $option ) 
+			|| empty( $option[ $id ] ) 
+		) {
+			WP_CLI::warning( sprintf( 'No record of last update to `%s`', $id ) );
+			return;
+		}
+		
+		$updated = $option[ $id ];
+		
+		if ( empty( $assoc['seconds'] ) ) {
+			$updated = date( 'c', $updated );
+		}
+		
+		WP_CLI::line( $updated );
+	}
+
+	/**
+	 * CLI command: admin-last-updated list
+	 *
+	 * @param array $args
+	 * @param array $assoc
+	 *
+	 * @return void
+	 *
+	 * @todo test
+	 */
+	public function cli__list( array $args, array $assoc = array() ) : void {
+		$option = ( array ) get_option( self::OPTION_NAME, array() );
+		
+		if ( empty( $option ) ) {
+			WP_CLI::warning( sprintf( 'No records', $id ) );
+			return;
+		}
+		
+		$items = array();
+		
+		foreach ( $option as $id => $seconds ) {
+			if ( empty( $seconds ) ) {
+				continue;
+			}
+			
+			$items[] = array(
+				'id'        => $id,
+				'seconds'   => $seconds,
+				'timestamp' => date( 'c', $seconds ),
+			);
+		}
+		
+		WP_CLI\Utils\format_items(
+			WP_CLI\Utils\get_flag_value( 'format', $assoc, 'table' ),
+			$items,
+			array( 'id', 'seconds', 'timestamp' )
+		);
+	}
+
+}
+
+if ( 
+	! is_admin() 
+	&& ( 
+		   ! defined( 'WP_CLI' ) 
+		|| ! WP_CLI 
+	) 
+) {
+	return;
+}
+
+CSSLLC_Admin_Last_Updated::init();
\ No newline at end of file