diff --git a/changelog.d/10867.misc b/changelog.d/10867.misc
new file mode 100644
index 000000000..01e51fbc6
--- /dev/null
+++ b/changelog.d/10867.misc
@@ -0,0 +1 @@
+Add type hints to `synapse.http.site`.
diff --git a/synapse/http/site.py b/synapse/http/site.py
index c665a9d5d..dd4c749e1 100644
--- a/synapse/http/site.py
+++ b/synapse/http/site.py
@@ -21,7 +21,7 @@ from zope.interface import implementer
 
 from twisted.internet.interfaces import IAddress, IReactorTime
 from twisted.python.failure import Failure
-from twisted.web.resource import IResource
+from twisted.web.resource import IResource, Resource
 from twisted.web.server import Request, Site
 
 from synapse.config.server import ListenerConfig
@@ -61,7 +61,7 @@ class SynapseRequest(Request):
         logcontext: the log context for this request
     """
 
-    def __init__(self, channel, *args, max_request_body_size=1024, **kw):
+    def __init__(self, channel, *args, max_request_body_size: int = 1024, **kw):
         Request.__init__(self, channel, *args, **kw)
         self._max_request_body_size = max_request_body_size
         self.site: SynapseSite = channel.site
@@ -83,13 +83,13 @@ class SynapseRequest(Request):
         self._is_processing = False
 
         # the time when the asynchronous request handler completed its processing
-        self._processing_finished_time = None
+        self._processing_finished_time: Optional[float] = None
 
         # what time we finished sending the response to the client (or the connection
         # dropped)
-        self.finish_time = None
+        self.finish_time: Optional[float] = None
 
-    def __repr__(self):
+    def __repr__(self) -> str:
         # We overwrite this so that we don't log ``access_token``
         return "<%s at 0x%x method=%r uri=%r clientproto=%r site=%r>" % (
             self.__class__.__name__,
@@ -100,7 +100,7 @@ class SynapseRequest(Request):
             self.site.site_tag,
         )
 
-    def handleContentChunk(self, data):
+    def handleContentChunk(self, data: bytes) -> None:
         # we should have a `content` by now.
         assert self.content, "handleContentChunk() called before gotLength()"
         if self.content.tell() + len(data) > self._max_request_body_size:
@@ -139,7 +139,7 @@ class SynapseRequest(Request):
         # If there's no authenticated entity, it was the requester.
         self.logcontext.request.authenticated_entity = authenticated_entity or requester
 
-    def get_request_id(self):
+    def get_request_id(self) -> str:
         return "%s-%i" % (self.get_method(), self.request_seq)
 
     def get_redacted_uri(self) -> str:
@@ -205,7 +205,7 @@ class SynapseRequest(Request):
 
         return None, None
 
-    def render(self, resrc):
+    def render(self, resrc: Resource) -> None:
         # this is called once a Resource has been found to serve the request; in our
         # case the Resource in question will normally be a JsonResource.
 
@@ -282,7 +282,7 @@ class SynapseRequest(Request):
             if self.finish_time is not None:
                 self._finished_processing()
 
-    def finish(self):
+    def finish(self) -> None:
         """Called when all response data has been written to this Request.
 
         Overrides twisted.web.server.Request.finish to record the finish time and do
@@ -295,7 +295,7 @@ class SynapseRequest(Request):
             with PreserveLoggingContext(self.logcontext):
                 self._finished_processing()
 
-    def connectionLost(self, reason):
+    def connectionLost(self, reason: Union[Failure, Exception]) -> None:
         """Called when the client connection is closed before the response is written.
 
         Overrides twisted.web.server.Request.connectionLost to record the finish time and
@@ -327,7 +327,7 @@ class SynapseRequest(Request):
             if not self._is_processing:
                 self._finished_processing()
 
-    def _started_processing(self, servlet_name):
+    def _started_processing(self, servlet_name: str) -> None:
         """Record the fact that we are processing this request.
 
         This will log the request's arrival. Once the request completes,
@@ -354,9 +354,11 @@ class SynapseRequest(Request):
             self.get_redacted_uri(),
         )
 
-    def _finished_processing(self):
+    def _finished_processing(self) -> None:
         """Log the completion of this request and update the metrics"""
         assert self.logcontext is not None
+        assert self.finish_time is not None
+
         usage = self.logcontext.get_resource_usage()
 
         if self._processing_finished_time is None:
@@ -437,7 +439,7 @@ class XForwardedForRequest(SynapseRequest):
     _forwarded_for: "Optional[_XForwardedForAddress]" = None
     _forwarded_https: bool = False
 
-    def requestReceived(self, command, path, version):
+    def requestReceived(self, command: bytes, path: bytes, version: bytes) -> None:
         # this method is called by the Channel once the full request has been
         # received, to dispatch the request to a resource.
         # We can use it to set the IP address and protocol according to the
@@ -445,7 +447,7 @@ class XForwardedForRequest(SynapseRequest):
         self._process_forwarded_headers()
         return super().requestReceived(command, path, version)
 
-    def _process_forwarded_headers(self):
+    def _process_forwarded_headers(self) -> None:
         headers = self.requestHeaders.getRawHeaders(b"x-forwarded-for")
         if not headers:
             return
@@ -470,7 +472,7 @@ class XForwardedForRequest(SynapseRequest):
             )
             self._forwarded_https = True
 
-    def isSecure(self):
+    def isSecure(self) -> bool:
         if self._forwarded_https:
             return True
         return super().isSecure()
@@ -545,14 +547,16 @@ class SynapseSite(Site):
         proxied = config.http_options.x_forwarded
         request_class = XForwardedForRequest if proxied else SynapseRequest
 
-        def request_factory(channel, queued) -> Request:
+        def request_factory(channel, queued: bool) -> Request:
             return request_class(
-                channel, max_request_body_size=max_request_body_size, queued=queued
+                channel,
+                max_request_body_size=max_request_body_size,
+                queued=queued,
             )
 
         self.requestFactory = request_factory  # type: ignore
         self.access_logger = logging.getLogger(logger_name)
         self.server_version_string = server_version_string.encode("ascii")
 
-    def log(self, request):
+    def log(self, request: SynapseRequest) -> None:
         pass