diff --git a/backend/src/structs/landmarks.py b/backend/src/structs/landmarks.py
index 71111a1..f6db9ac 100644
--- a/backend/src/structs/landmarks.py
+++ b/backend/src/structs/landmarks.py
@@ -1,6 +1,5 @@
-from typing import Optional
+from typing import Optional, Literal
 from pydantic import BaseModel, Field
-from .landmarktype import LandmarkType
 
 from uuid import uuid4
 
@@ -9,7 +8,7 @@ class Landmark(BaseModel) :
     
     # Properties of the landmark
     name : str
-    type: LandmarkType      # De facto mapping depending on how the query was executed with overpass. Should still EXACTLY correspond to the preferences
+    type: Literal['sightseeing', 'nature', 'shopping']
     location : tuple
     osm_type : str
     osm_id : int
@@ -24,10 +23,15 @@ class Landmark(BaseModel) :
     
     # Additional properties depending on specific tour
     must_do : bool
+    must_avoid : bool
     is_secondary : Optional[bool] = False                       # TODO future   
     
     time_to_reach_next : Optional[int] = 0                      # TODO fix this in existing code
     next_uuid : Optional[str] = None                            # TODO implement this ASAP
 
     def __hash__(self) -> int:
-        return self.uuid.int
\ No newline at end of file
+        return self.uuid.int
+    
+    def __str__(self) -> str:
+        return f'Landmark: [{self.name}, {self.location}, {self.attractiveness}]'
+    
diff --git a/backend/src/structs/landmarktype.py b/backend/src/structs/landmarktype.py
deleted file mode 100644
index 8a63a1b..0000000
--- a/backend/src/structs/landmarktype.py
+++ /dev/null
@@ -1,4 +0,0 @@
-from pydantic import BaseModel
-
-class LandmarkType(BaseModel):
-    landmark_type: str
\ No newline at end of file
diff --git a/backend/src/structs/preferences.py b/backend/src/structs/preferences.py
index 500ebec..ff25007 100644
--- a/backend/src/structs/preferences.py
+++ b/backend/src/structs/preferences.py
@@ -1,9 +1,9 @@
 from pydantic import BaseModel
-from .landmarktype import LandmarkType
+from typing import Optional, Literal
 
 class Preference(BaseModel) :
     name: str
-    type: LandmarkType  # should match the attributes of the Preferences class
+    type: Literal['sightseeing', 'nature', 'shopping']
     score: int          # score could be from 1 to 5
 
 # Input for optimization
@@ -17,12 +17,5 @@ class Preferences(BaseModel) :
     # Shopping (diriger plutôt vers des zones / rues commerçantes)
     shopping : Preference
 
-"""    # Food (price low or high. Combien on veut dépenser pour manger à midi/soir)
-    food_budget : Preference
-    
-    # Tolérance au détour (ce qui détermine (+ ou -) le chemin emprunté)
-    detour_tol : Preference"""
-
-
-
-
+    max_time_minute: Optional[int] = 6*60 
+    detour_tolerance_minute: Optional[int] = 0