diff --git a/zerver/lib/events.py b/zerver/lib/events.py
index 5658ba5dec..01b3ddcfe5 100644
--- a/zerver/lib/events.py
+++ b/zerver/lib/events.py
@@ -1316,7 +1316,7 @@ def apply_event(
 
 
 def do_events_register(
-    user_profile: UserProfile,
+    user_profile: Optional[UserProfile],
     realm: Realm,
     user_client: Client,
     apply_markdown: bool = True,
@@ -1356,6 +1356,33 @@ def do_events_register(
     else:
         event_types_set = None
 
+    if user_profile is None:
+        # TODO: Unify this with the below code path once if/when we
+        # support requesting an event queue for spectators.
+        #
+        # Doing so likely has a prerequisite of making this function's
+        # caller enforce client_gravatar=False,
+        # include_subscribers=False and include_streams=False.
+        ret = fetch_initial_state_data(
+            user_profile,
+            realm=realm,
+            event_types=event_types_set,
+            queue_id=None,
+            # Force client_gravatar=False for security reasons.
+            client_gravatar=False,
+            user_avatar_url_field_optional=user_avatar_url_field_optional,
+            user_settings_object=user_settings_object,
+            # slim_presence is a noop, because presence is not included.
+            slim_presence=True,
+            # Force include_subscribers=False for security reasons.
+            include_subscribers=False,
+            # Force include_streams=False for security reasons.
+            include_streams=False,
+        )
+
+        post_process_state(user_profile, ret, notification_settings_null=False)
+        return ret
+
     # Fill up the UserMessage rows if a soft-deactivated user has returned
     reactivate_user_if_soft_deactivated(user_profile)
 
diff --git a/zerver/openapi/zulip.yaml b/zerver/openapi/zulip.yaml
index 9ab52df11f..3a2ab0c18e 100644
--- a/zerver/openapi/zulip.yaml
+++ b/zerver/openapi/zulip.yaml
@@ -9207,8 +9207,12 @@ paths:
                       msg: {}
                       queue_id:
                         type: string
+                        nullable: true
                         description: |
                           The ID of the queue that has been allocated for your client.
+
+                          Will be None only for unauthenticated access in realms that have
+                          enabled the [public access option](/help/public-access-option).
                       last_event_id:
                         type: integer
                         description: |
diff --git a/zerver/tests/test_event_system.py b/zerver/tests/test_event_system.py
index fc0bc5e00d..ebf8c412c9 100644
--- a/zerver/tests/test_event_system.py
+++ b/zerver/tests/test_event_system.py
@@ -143,6 +143,23 @@ class EventsEndpointTest(ZulipTestCase):
         self.assertEqual(result_dict["realm_emoji"], [])
         self.assertEqual(result_dict["queue_id"], "15:13")
 
+    def test_events_register_spectators(self) -> None:
+        # Verify that POST /register works for spectators, but not for
+        # normal users.
+        with self.settings(WEB_PUBLIC_STREAMS_ENABLED=False):
+            result = self.client_post("/json/register", dict())
+            self.assert_json_error(
+                result,
+                "Not logged in: API authentication or user session required",
+                status_code=401,
+            )
+
+        result = self.client_post("/json/register", dict())
+        self.assert_json_success(result)
+        result_dict = result.json()
+        self.assertEqual(result_dict["queue_id"], None)
+        self.assertEqual(result_dict["realm_uri"], "http://zulip.testserver")
+
     def test_events_register_endpoint_all_public_streams_access(self) -> None:
         guest_user = self.example_user("polonius")
         normal_user = self.example_user("hamlet")
diff --git a/zerver/views/events_register.py b/zerver/views/events_register.py
index a7b4ea3290..a9155af31d 100644
--- a/zerver/views/events_register.py
+++ b/zerver/views/events_register.py
@@ -1,10 +1,12 @@
-from typing import Dict, Optional, Sequence
+from typing import Dict, Optional, Sequence, Union
 
+from django.contrib.auth.models import AnonymousUser
 from django.http import HttpRequest, HttpResponse
 from django.utils.translation import gettext as _
 
+from zerver.context_processors import get_valid_realm_from_request
 from zerver.lib.events import do_events_register
-from zerver.lib.exceptions import JsonableError
+from zerver.lib.exceptions import JsonableError, MissingAuthenticationError
 from zerver.lib.request import REQ, RequestNotes, has_request_variables
 from zerver.lib.response import json_success
 from zerver.lib.validator import check_bool, check_dict, check_int, check_list, check_string
@@ -35,7 +37,7 @@ NarrowT = Sequence[Sequence[str]]
 @has_request_variables
 def events_register_backend(
     request: HttpRequest,
-    user_profile: UserProfile,
+    maybe_user_profile: Union[UserProfile, AnonymousUser],
     apply_markdown: bool = REQ(default=False, json_validator=check_bool),
     client_gravatar: bool = REQ(default=True, json_validator=check_bool),
     slim_presence: bool = REQ(default=False, json_validator=check_bool),
@@ -71,11 +73,24 @@ def events_register_backend(
     ),
     queue_lifespan_secs: int = REQ(json_validator=check_int, default=0, documentation_pending=True),
 ) -> HttpResponse:
-    if all_public_streams and not user_profile.can_access_public_streams():
-        raise JsonableError(_("User not authorized for this query"))
+    if maybe_user_profile.is_authenticated:
+        user_profile = maybe_user_profile
+        assert isinstance(user_profile, UserProfile)
+        realm = user_profile.realm
 
-    all_public_streams = _default_all_public_streams(user_profile, all_public_streams)
-    narrow = _default_narrow(user_profile, narrow)
+        if all_public_streams and not user_profile.can_access_public_streams():
+            raise JsonableError(_("User not authorized for this query"))
+
+        all_public_streams = _default_all_public_streams(user_profile, all_public_streams)
+        narrow = _default_narrow(user_profile, narrow)
+    else:
+        user_profile = None
+        realm = get_valid_realm_from_request(request)
+
+        if not realm.allow_web_public_streams_access():
+            raise MissingAuthenticationError()
+
+        all_public_streams = False
 
     if client_capabilities is None:
         client_capabilities = {}
@@ -85,7 +100,7 @@ def events_register_backend(
 
     ret = do_events_register(
         user_profile,
-        user_profile.realm,
+        realm,
         client,
         apply_markdown,
         client_gravatar,
diff --git a/zproject/urls.py b/zproject/urls.py
index a790f1a963..3677801921 100644
--- a/zproject/urls.py
+++ b/zproject/urls.py
@@ -469,7 +469,7 @@ v1_api_and_json_patterns = [
     rest_path("users/me/subscriptions/muted_topics", PATCH=update_muted_topic),
     rest_path("users/me/muted_users/<int:muted_user_id>", POST=mute_user, DELETE=unmute_user),
     # used to register for an event queue in tornado
-    rest_path("register", POST=events_register_backend),
+    rest_path("register", POST=(events_register_backend, {"allow_anonymous_user_web"})),
     # events -> zerver.tornado.views
     rest_path("events", GET=get_events, DELETE=cleanup_event_queue),
     # report -> zerver.views.report