diff --git a/backend/Pipfile b/backend/Pipfile
index f02576b..7ffd4d8 100644
--- a/backend/Pipfile
+++ b/backend/Pipfile
@@ -8,5 +8,6 @@ numpy = "*"
 scipy = "*"
 fastapi = "*"
 osmpythontools = "*"
+pydantic = "*"
 
 [dev-packages]
diff --git a/backend/Pipfile.lock b/backend/Pipfile.lock
index f07cd8e..d41ed09 100644
--- a/backend/Pipfile.lock
+++ b/backend/Pipfile.lock
@@ -1,7 +1,7 @@
 {
     "_meta": {
         "hash": {
-            "sha256": "15cc819367b908ccf7d61e3f2b45574c248556600dfeaa795e19045d6781fe90"
+            "sha256": "4293390eadd968364de0b376810eb66c68a4876d24a87987dc61010ad92c5712"
         },
         "pipfile-spec": 6,
         "requires": {},
@@ -890,6 +890,7 @@
                 "sha256:71b2945998f9c9b7919a45bde9a50397b289937d215ae141c1d0903ba7149fd7",
                 "sha256:834ab954175f94e6e68258537dc49402c4a5e9d0409b9f1b86b7e934a8372de7"
             ],
+            "index": "pypi",
             "markers": "python_version >= '3.8'",
             "version": "==2.7.2"
         },
diff --git a/backend/app/__init__.py b/backend/app/__init__.py
deleted file mode 100644
index e69de29..0000000
diff --git a/backend/app/__pycache__/__init__.cpython-310.pyc b/backend/app/__pycache__/__init__.cpython-310.pyc
deleted file mode 100644
index 678d7d0..0000000
Binary files a/backend/app/__pycache__/__init__.cpython-310.pyc and /dev/null differ
diff --git a/backend/app/__pycache__/main.cpython-310.pyc b/backend/app/__pycache__/main.cpython-310.pyc
deleted file mode 100644
index cd67059..0000000
Binary files a/backend/app/__pycache__/main.cpython-310.pyc and /dev/null differ
diff --git a/backend/app/dependencies.py b/backend/app/dependencies.py
deleted file mode 100644
index 2cb6801..0000000
--- a/backend/app/dependencies.py
+++ /dev/null
@@ -1 +0,0 @@
-import app.src
\ No newline at end of file
diff --git a/backend/app/main.py b/backend/app/main.py
deleted file mode 100644
index 257d572..0000000
--- a/backend/app/main.py
+++ /dev/null
@@ -1,34 +0,0 @@
-from .src.optimizer import solve_optimization
-from .src.landmarks_manager import Landmark
-from fastapi import FastAPI
-
-app = FastAPI()
-
-
-@app.get("/optimize/{max_steps}/{print_details}")
-def main(max_steps: int, print_details: bool):
-    
-    # CONSTRAINT TO RESPECT MAX NUMBER OF STEPS
-    #max_steps = 16
-
-
-    # Initialize all landmarks (+ start and goal). Order matters here
-    landmarks = []
-    landmarks.append(Landmark("départ", -1, (0, 0)))
-    landmarks.append(Landmark("tour eiffel", 99, (0,2)))                           # PUT IN JSON
-    landmarks.append(Landmark("arc de triomphe", 99, (0,4)))
-    landmarks.append(Landmark("louvre", 99, (0,6)))
-    landmarks.append(Landmark("montmartre", 99, (0,10)))
-    landmarks.append(Landmark("concorde", 99, (0,8)))
-    landmarks.append(Landmark("arrivée", -1, (0, 0)))
-
-
-    visiting_order = solve_optimization(landmarks, max_steps, print_details)
-
-    #return visiting_order
-
-    return("max steps :", max_steps, "\n", visiting_order)
-
-
-"""if __name__ == "__main__":
-    main()"""
\ No newline at end of file
diff --git a/backend/app/src/__init__.py b/backend/app/src/__init__.py
deleted file mode 100644
index e69de29..0000000
diff --git a/backend/app/src/__pycache__/__init__.cpython-310.pyc b/backend/app/src/__pycache__/__init__.cpython-310.pyc
deleted file mode 100644
index 3c06a08..0000000
Binary files a/backend/app/src/__pycache__/__init__.cpython-310.pyc and /dev/null differ
diff --git a/backend/app/src/__pycache__/optimizer.cpython-310.pyc b/backend/app/src/__pycache__/optimizer.cpython-310.pyc
deleted file mode 100644
index e60b82c..0000000
Binary files a/backend/app/src/__pycache__/optimizer.cpython-310.pyc and /dev/null differ
diff --git a/backend/app/src/landmarks_manager.py b/backend/src/landmarks_manager.py
similarity index 91%
rename from backend/app/src/landmarks_manager.py
rename to backend/src/landmarks_manager.py
index 0c3a0e2..c8207b4 100644
--- a/backend/app/src/landmarks_manager.py
+++ b/backend/src/landmarks_manager.py
@@ -1,6 +1,7 @@
 from OSMPythonTools.api import Api
 from OSMPythonTools.overpass import Overpass
 from dataclasses import dataclass
+from pydantic import BaseModel
 
 
 # Defines the landmark class (aka some place there is to visit)
@@ -10,8 +11,7 @@ class Landmarkkkk :
     attractiveness : int
     id : int
     
-@dataclass
-class Landmark :
+class Landmark(BaseModel) :
     name : str
     attractiveness : int
     loc : tuple
diff --git a/backend/src/main.py b/backend/src/main.py
new file mode 100644
index 0000000..d267aa8
--- /dev/null
+++ b/backend/src/main.py
@@ -0,0 +1,42 @@
+from optimizer import solve_optimization
+from .structs.landmarks import LandmarkTest
+from .structs.preferences import Preferences
+from fastapi import FastAPI
+
+app = FastAPI()
+
+# This should become main at some point
+@app.post("optimizer/{longitude}/{latitude}")
+def get_data(longitude: float, latitude: float, preferences: Preferences) :
+    # From frontend get longitude, latitude and prefence list
+
+    return
+
+@app.get("optimizer/{max_steps}/{print_details}")
+def main(max_steps: int, print_details: bool):
+    
+    # CONSTRAINT TO RESPECT MAX NUMBER OF STEPS
+    #max_steps = 16
+
+
+    # Initialize all landmarks (+ start and goal). Order matters here
+    landmarks = []
+    landmarks.append(LandmarkTest("départ", -1, (0, 0)))
+    landmarks.append(LandmarkTest("tour eiffel", 99, (0,2)))                           # PUT IN JSON
+    landmarks.append(LandmarkTest("arc de triomphe", 99, (0,4)))
+    landmarks.append(LandmarkTest("louvre", 99, (0,6)))
+    landmarks.append(LandmarkTest("montmartre", 99, (0,10)))
+    landmarks.append(LandmarkTest("concorde", 99, (0,8)))
+    landmarks.append(LandmarkTest("arrivée", -1, (0, 0)))
+
+
+    visiting_order = solve_optimization(landmarks, max_steps, print_details)
+
+    #return visiting_order
+
+    # should return landmarks = the list of Landmark (ordered list)
+    return("max steps :", max_steps, "\n", visiting_order)
+
+
+"""if __name__ == "__main__":
+    main()"""
\ No newline at end of file
diff --git a/backend/app/src/main_example.py b/backend/src/main_example.py
similarity index 100%
rename from backend/app/src/main_example.py
rename to backend/src/main_example.py
diff --git a/backend/app/src/optimizer.py b/backend/src/optimizer.py
similarity index 100%
rename from backend/app/src/optimizer.py
rename to backend/src/optimizer.py
diff --git a/backend/src/structs/landmarks.py b/backend/src/structs/landmarks.py
new file mode 100644
index 0000000..cb262d9
--- /dev/null
+++ b/backend/src/structs/landmarks.py
@@ -0,0 +1,24 @@
+from pydantic import BaseModel
+from .landmarktype import LandmarkType
+from .preferences import Preferences
+
+class LandmarkTest(BaseModel) :
+    name : str
+    attractiveness : int
+    loc : tuple
+
+# Output to frontend
+class Landmark(BaseModel) :
+    name : str
+    type: LandmarkType      # De facto mapping depending on how the query was executed with overpass. Should still EXACTLY correspond to the preferences
+    location : tuple
+
+
+    def score(preferences: Preferences):
+        # loop through the preferences and assign a score
+
+
+        return 29
+
+
+
diff --git a/backend/src/structs/landmarktype.py b/backend/src/structs/landmarktype.py
new file mode 100644
index 0000000..8a63a1b
--- /dev/null
+++ b/backend/src/structs/landmarktype.py
@@ -0,0 +1,4 @@
+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
new file mode 100644
index 0000000..94e0836
--- /dev/null
+++ b/backend/src/structs/preferences.py
@@ -0,0 +1,28 @@
+from pydantic import BaseModel
+from .landmarktype import LandmarkType
+
+class Preference(BaseModel) :
+    name: str
+    type: LandmarkType
+    score: int
+
+# Input for optimization
+class Preferences(BaseModel) :
+    # Sightseeing / History & Culture (Musées, bâtiments historiques, opéras, églises)
+    sightseeing : Preference
+
+    # Nature (parcs, jardins, rivières, plages)
+    nature: Preference
+
+    # 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
+
+
+
+