diff --git a/melisa/__init__.py b/melisa/__init__.py
index 0864f2a..2636d32 100644
--- a/melisa/__init__.py
+++ b/melisa/__init__.py
@@ -12,5 +12,4 @@ __title__ = "Melisa"
 __description__ = "Cache-optimized Discord microframework for Python 3"
 __author__ = "MelisaDev"
 __license__ = "MIT"
-__version__ = '0.0.1.dev2'
-
+__version__ = "0.0.1.dev2"
diff --git a/melisa/cache.py b/melisa/cache.py
index 006f34a..b79cd1a 100644
--- a/melisa/cache.py
+++ b/melisa/cache.py
@@ -13,7 +13,8 @@ from .utils.snowflake import Snowflake
 
 
 class ChannelsCachingPolicy(Enum):
-    """"Channels caching policy"""
+    """ "Channels caching policy"""
+
     ALL = "all"
     NONE = "none"
     GUILD_TEXT = 0
@@ -42,11 +43,7 @@ class CacheManager:
 
         # Some default values
         if policies is None:
-            policies = {
-                "channels": [
-                    ChannelsCachingPolicy.GUILD_TEXT
-                ]
-            }
+            policies = {"channels": [ChannelsCachingPolicy.GUILD_TEXT]}
 
         self._policies = policies
 
@@ -113,7 +110,9 @@ class CacheManager:
                 policy = [int(x.value) for x in policy]
 
                 channels = filter(
-                    lambda channel: channel.type is not None and int(channel.type) in policy, channels
+                    lambda channel: channel.type is not None
+                    and int(channel.type) in policy,
+                    channels,
                 )
 
             for sym in channels:
diff --git a/melisa/models/guild/guild.py b/melisa/models/guild/guild.py
index 2c6f7d8..655ece0 100644
--- a/melisa/models/guild/guild.py
+++ b/melisa/models/guild/guild.py
@@ -15,7 +15,7 @@ from .channel import (
 
 
 from .member import GuildMember
-from ... import Role
+from .role import Role
 from ...utils import Snowflake, Timestamp
 from ...utils.api_model import APIModelBase
 from ...utils.conversion import try_enum
@@ -466,6 +466,7 @@ class Guild(APIModelBase):
         self.threads = {}
         self.channels = {}
         self.members = {}
+        self.roles = {}
 
         for member in data.get("members", []):
             member = GuildMember.from_dict(member)
@@ -480,7 +481,7 @@ class Guild(APIModelBase):
 
         for role in data.get("roles", []):
             role["guild_id"] = self.id
-            self.roles[Snowflake(int(role.id))] = Role.from_dict(role)
+            self.roles[Snowflake(int(role["id"]))] = Role.from_dict(role)
 
         return self
 
diff --git a/melisa/models/user/user.py b/melisa/models/user/user.py
index ea0bced..26be355 100644
--- a/melisa/models/user/user.py
+++ b/melisa/models/user/user.py
@@ -210,11 +210,10 @@ class User(APIModelBase):
         """:class:`str`: The user's mention string. (<@id>)"""
         return "<@{}>".format(self.id)
 
-    def avatar_url(self) -> str:
+    def avatar_url(self, *, size: int = 1024, image_format: str = None) -> str:
+        # ToDo: Add Docstrings
         """Avatar url (from the Discord CDN server)"""
-        return "https://cdn.discordapp.com/avatars/{}/{}.png?size=1024".format(
-            self.id, self.avatar
-        )
+        return self._client.rest.cdn.avatar_url(self.id, self.avatar, size=size, image_format=image_format)
 
     async def create_dm_channel(self):
         # ToDo: Add docstrings
diff --git a/melisa/rest.py b/melisa/rest.py
index e02471f..690ffea 100644
--- a/melisa/rest.py
+++ b/melisa/rest.py
@@ -45,10 +45,18 @@ class RESTApp:
     ----------
     token: :class:`str`
         The token to authorize (you can found it in the developer portal)
+    default_image_format: :class:`str`
+        Default image format
+
+    Attributes
+    -----------
+    cdn: :class:`~melisa.rest.CDNBuilder`
+        CDN Builder to build images
     """
 
-    def __init__(self, token: str):
+    def __init__(self, token: str, default_image_format: str = None):
         self._http: HTTPClient = HTTPClient(token)
+        self.cdn = CDNBuilder(default_image_format)
 
     async def fetch_user(self, user_id: Union[Snowflake, int, str]) -> User:
         """|coro|
@@ -652,3 +660,31 @@ class RESTApp:
             f"guilds/{guild_id}/members/{user_id}/roles/{role_id}",
             headers={"X-Audit-Log-Reason": reason},
         )
+
+
+class CDNBuilder:
+    """Can be used to build images
+
+    Parameters
+    ----------
+    default_image_format: :class:`str`
+        Default image format
+    """
+
+    # ToDo: Add docstrings
+
+    BASE_URL = "https://cdn.discordapp.com"
+
+    def __init__(self, default_image_format: str = None):
+        self.dif = default_image_format if default_image_format is not None else "png"
+
+    def avatar_url(
+        self, user_id: str, _hash: str, *, size: int = 1024, image_format: str = None
+    ):
+        return "{}/avatars/{}/{}.{}?size={}".format(
+            self.BASE_URL,
+            user_id,
+            _hash,
+            image_format if image_format is not None else self.dif,
+            size,
+        )