diff --git a/src/c3nav/mapdata/api.py b/src/c3nav/mapdata/api.py
index bdfe89c7..717c512a 100644
--- a/src/c3nav/mapdata/api.py
+++ b/src/c3nav/mapdata/api.py
@@ -418,7 +418,9 @@ class UpdatesViewSet(GenericViewSet):
         except ValueError:
             cache.set('api_updates_fetch_requests', 0, None)
 
+        from c3nav.site.models import SiteUpdate
         response = Response({
+            'last_site_update': SiteUpdate.last_update(),
             'last_map_update': MapUpdate.current_processed_cache_key(),
             'user': get_user_data(request),
         })
diff --git a/src/c3nav/mapdata/models/update.py b/src/c3nav/mapdata/models/update.py
index dc536442..e5590a98 100644
--- a/src/c3nav/mapdata/models/update.py
+++ b/src/c3nav/mapdata/models/update.py
@@ -163,7 +163,7 @@ class MapUpdate(models.Model):
                 new_update.save()
 
             transaction.on_commit(
-                lambda: cache.set('mapdata:last_processed_update', new_updates[-1].to_tuple, 300)
+                lambda: cache.set('mapdata:last_processed_update', new_updates[-1].to_tuple, None)
             )
 
             return new_updates
@@ -188,7 +188,7 @@ class MapUpdate(models.Model):
 
         if new:
             transaction.on_commit(
-                lambda: cache.set('mapdata:last_update', self.to_tuple, 300)
+                lambda: cache.set('mapdata:last_update', self.to_tuple, None)
             )
             if settings.HAS_CELERY:
                 transaction.on_commit(
diff --git a/src/c3nav/site/management/commands/createsiteupdate.py b/src/c3nav/site/management/commands/createsiteupdate.py
index bdc7a607..893cddba 100644
--- a/src/c3nav/site/management/commands/createsiteupdate.py
+++ b/src/c3nav/site/management/commands/createsiteupdate.py
@@ -8,7 +8,7 @@ class Command(BaseCommand):
         result = input('Type YES to create a new site update: ')
 
         if result == 'YES':
-            from c3nav.mapdata.models import SiteUpdate
+            from c3nav.site.models import SiteUpdate
             SiteUpdate.objects.create()
             print('New site update created.')
         else:
diff --git a/src/c3nav/site/models.py b/src/c3nav/site/models.py
index 025cbf1a..04bc34f1 100644
--- a/src/c3nav/site/models.py
+++ b/src/c3nav/site/models.py
@@ -1,6 +1,8 @@
+from contextlib import contextmanager
+
 from django.conf import settings
 from django.core.cache import cache
-from django.db import models
+from django.db import models, transaction
 from django.db.models import Q
 from django.utils import timezone
 from django.utils.translation import ugettext_lazy as _
@@ -50,3 +52,42 @@ class SiteUpdate(models.Model):
     A site update that asks the user to reload the page.
     """
     created = models.DateTimeField(auto_now_add=True, verbose_name=_('create'))
+
+    class Meta:
+        verbose_name = _('Site update')
+        verbose_name_plural = _('Site updates')
+        default_related_name = 'siteupdates'
+        get_latest_by = 'created'
+
+    @classmethod
+    @contextmanager
+    def lock(cls):
+        with transaction.atomic():
+            try:
+                yield cls.objects.select_for_update().get(pk=cls.objects.earliest().pk)
+            except cls.DoesNotExist:
+                yield
+
+    @classmethod
+    def last_update(cls):
+        last_update = cache.get('site:last_site_update', None)
+        if last_update is not None:
+            return last_update
+        with cls.lock():
+            try:
+                last_update = cls.objects.latest()
+            except cls.DoesNotExist:
+                last_update = None
+            else:
+                last_update = last_update.pk
+            cache.set('site:last_site_update', last_update, None)
+        return last_update
+
+    def save(self, **kwargs):
+        new = self.pk is None
+        with transaction.atomic():
+            super().save(**kwargs)
+            if new:
+                transaction.on_commit(
+                    lambda: cache.set('site:last_site_update', self.pk, None)
+                )
diff --git a/src/c3nav/site/static/site/js/c3nav.js b/src/c3nav/site/static/site/js/c3nav.js
index 853c63b3..94a0891b 100644
--- a/src/c3nav/site/static/site/js/c3nav.js
+++ b/src/c3nav/site/static/site/js/c3nav.js
@@ -68,6 +68,9 @@ c3nav = {
             state = JSON.parse($main.attr('data-state'));
         c3nav.embed = $main.is('[data-embed]');
 
+        c3nav.last_site_update = JSON.parse($main.attr('data-last-site-update'));
+        c3nav.new_site_update = false;
+
         history.replaceState(state, window.location.path);
         c3nav.load_state(state, true);
         c3nav.update_map_locations();
@@ -549,10 +552,13 @@ c3nav = {
             // console.log('state pushed');
             history.pushState(state, '', url);
         }
+
+        c3nav._maybe_load_site_update(state);
     },
     _onpopstate: function (e) {
         // console.log('state popped');
         c3nav.load_state(e.state);
+        c3nav._maybe_load_site_update(e.state);
     },
     load_state: function (state, nofly) {
         if (state.modal) {
@@ -886,22 +892,24 @@ c3nav = {
         }
     },
 
-    open_modal: function (content) {
+    modal_noclose: false,
+    open_modal: function (content, no_close) {
+        c3nav.modal_noclose = no_close;
         var $modal = $('#modal');
-        c3nav._set_modal_content(content);
+        c3nav._set_modal_content(content, no_close);
         if (!$modal.is('.show')) {
             c3nav._push_state({modal: true, sidebar: true});
             $modal.addClass('show');
         }
     },
-    _set_modal_content: function(content) {
+    _set_modal_content: function(content, no_close) {
         $('#modal').toggleClass('loading', !content)
             .find('#modal-content')
-            .html('<button class="button-clear material-icons" id="close-modal">clear</button>')
+            .html((!no_close) ? '<button class="button-clear material-icons" id="close-modal">clear</button>' :'')
             .append(content || '');
     },
     _modal_click: function(e) {
-        if (e.target.id === 'modal' || e.target.id === 'close-modal') {
+        if (!c3nav.modal_noclose && (e.target.id === 'modal' || e.target.id === 'close-modal')) {
             history.back();
         }
     },
@@ -1168,8 +1176,26 @@ c3nav = {
     },
     _fetch_updates_callback: function (data) {
         c3nav.schedule_fetch_updates();
+        if (c3nav.last_site_update !== data.last_site_update) {
+            c3nav.new_site_update = true;
+            c3nav.last_site_update = data.last_site_update;
+            c3nav._maybe_load_site_update(c3nav.state);
+        }
         c3nav._set_user_data(data.user);
     },
+    _maybe_load_site_update: function(state) {
+        if (c3nav.new_site_update && !state.modal && (!state.routing || !state.origin || !state.destination)) {
+            c3nav._load_site_update();
+        }
+    },
+    _load_site_update: function() {
+        $('#modal-content').css({
+            width: 'auto',
+            minHeight: 0
+        });
+        c3nav.open_modal($('.reload-msg').html(), true);
+        window.location.reload();
+    },
     _set_user_data: function (data) {
         var $user = $('header #user');
         $user.find('span').text(data.title);
diff --git a/src/c3nav/site/templates/site/map.html b/src/c3nav/site/templates/site/map.html
index 468b0ec9..0ba8bce9 100644
--- a/src/c3nav/site/templates/site/map.html
+++ b/src/c3nav/site/templates/site/map.html
@@ -4,7 +4,7 @@
 {% load i18n %}
 
 {% block content %}
-    <main class="map" data-state="{{ state }}"{% if embed %} data-embed{% endif %}>
+    <main class="map" data-state="{{ state }}"{% if embed %} data-embed{% endif %} data-last-site-update="{{ last_site_update }}">
         <section id="attributions">
             {% if not embed %}
                 {% get_current_language as CURRENT_LANGUAGE %}
@@ -37,6 +37,9 @@
                     <button class="mobileclient-shortcut">{% trans 'create shortcut' %}</button>
                 </p>
             </section>
+            <section class="reload-msg">
+                <img src="{% static 'img/loader.gif' %}">
+            </section>
             <section id="sidebar">
                 <section id="search" class="loading">
                     <div class="location locationinput empty" id="origin-input">
diff --git a/src/c3nav/site/views.py b/src/c3nav/site/views.py
index 78596da5..225387f0 100644
--- a/src/c3nav/site/views.py
+++ b/src/c3nav/site/views.py
@@ -28,7 +28,7 @@ from c3nav.mapdata.models.locations import LocationRedirect, SpecificLocation
 from c3nav.mapdata.utils.locations import get_location_by_slug_for_request, levels_by_short_label_for_request
 from c3nav.mapdata.utils.user import get_user_data
 from c3nav.mapdata.views import set_tile_access_cookie
-from c3nav.site.models import Announcement
+from c3nav.site.models import Announcement, SiteUpdate
 
 
 def check_location(location: Optional[str], request) -> Optional[SpecificLocation]:
@@ -120,6 +120,7 @@ def map_index(request, mode=None, slug=None, slug2=None, details=None, options=N
         'tile_cache_server': settings.TILE_CACHE_SERVER,
         'initial_level': settings.INITIAL_LEVEL,
         'initial_bounds': json.dumps(settings.INITIAL_BOUNDS, separators=(',', ':')),
+        'last_site_update': json.dumps(SiteUpdate.last_update()),
         'embed': bool(embed),
     }