Happy to meet you here - so let's start with my guide and I hope some parts are helpful or new for you.

Note: As I've released already guides to some points I just put the links in the discriptions.

• The Secret Vault - A well hidden vault in the east of the map with a legendary weapon

• Spectacle Island - How to unlock the biggest Settlement in the Commonwealth

• Ballistic Weave - How to power up single articles of clothing and your armor

• Bosco's unique Mascot Head - Rescue the dog Teddy and how get this rare headwear

• The Abandoned Shack - South/west of the glowing sea, on the western border of the map you'll find a shack. Enter inside, loot the suitcase next to the dead body and you'll get the "Installation K-21B Key". With this you have now access through the nearby trapdoor to the Federal Surveillance Center K-21B.

• Fens Street Sewer - have fun by following the footsteps of the "Fens Phantom Killer". When you leave Diamond City Market turn to the right, pass the yellow bus on the left and turn to the right. You'll find the entrance to the sewer behind the brickwall on the right side.

• Another Hidden Vault - Quick travel to the Back Street Appereal in the north of Diamond City. Standing in front of the entrance, turn left, run around the building and follow the street to a blue trailer. On the left side you'll find the entrance to the Bridgeway Trust Bank. Enter the building and you can find the door to the vault in one of the backrooms next to a terminal (master lock). If you've Cait as a companion with you, she will be more than happy: Inside the vault there are 15 safes to unlock (novice till expert).

• Here there be Monsters! - a sidequest with an unique "must have" reward.

• When Pigs Fly - a sidequest to get up to 7 legendary and rare/unique weapons

• Message in a Bottle - an unmarked sidequest where you can find six bottles which hold secrets, waiting to be uncovered!

• The Big Dig- the quest will start after speaking to Bobbi No-Nose in a backstreet in Goodneighbor. As a reward you'll get the legendary minigun the Ashmaker (for the weapon have a look at the next chapter).

• Pickman's Gift - Visit the Pickman Gallery and get Pickman's Blade as a reward (for the weapon have a look at the next chapter).

• Gun Run - North/east of the museum of witchcraft you can find Barney Rook. Help him and you'll get the Reba II hunting rifle as a reward (for the weapon have a look at the next chapter).
  
  
• Pull the Plug – Go to the Thicket Excavations, east oft the Red Rocket Truck Stop. Speaking to Sully Mathis (next to a yellow pump) will unlock the quest. First you have now to unblock 3 underwater pipelines. The pipes can be found by following the bubbles on the surface and diving down. Each pipe can be fixed by simply turning a yellow valve located on the pipes. After fixing the pipes and speaking to Sully, you have to activate the circuit breaker to start the pump, what will spawn two mirelurks. After killing them speak to Sully again and the quest is done.
  
  Note: Visit the place, after you’ve done the quest, one in-game day later, you’ll find that the quarry has been drained and occupied by raiders.

• Spray N' Pray - a legendary submachine gun with an explosive effect, in which each shot deals 15 points of area explosive damage on impact. Sold by Cricket, a wandering caravan trader, who randomly appears on different places of the map.

• Le Fusil Terribles - a combat shotgun with +25% damage/limb damage but also significantly increased recoil. You can find it on a shelf in the captain's cabin on board of the Libertalia (in the far eastern area of the commonwealth).
  

• Reba II - a hunting rifle with 50% more damage against mirelurks and bugs. You'll get the Rifle as a reward after completing the Gun Run sidequest.

• Ashmaker - a minigun which sets target on fire for 15 points of damage. Nice side effect: The bullets produce orange tracers when fired. You'll get it as a reward after doing the The Big Dig sidequest.
  

• The Gainer - a .44 pistol which sets target on fire for 15 points of damage. Reward for solving the Vitale Pumphouse number puzzle. Go to the Finch Farm in the east and across the water (also to the east) you you'll find the pumphouse.

• Reckoning - a unique Ripper sold by Smiling Larry which bears the legendary Sentinel's effect and gives you 15% less damage while standing and not moving
  

• Laser Pistol Prototype UP77 "Limitless Potential" - a Laser pistol which can fire without reloading. You'll find it in the Secret Vault.

• Big Boy - This is a legendary version of the Fat Man with the Two Shot effect, allowing it to shoot two mini nukes at once for the cost of only one. Compatible with the MIRV launcher mod the Big Boy will shoot twelve mini nukes, while only consuming one. This weapon is available from the vendor Arturo Rodrigues in the Diamond City Market.
  

• Pickmans Blade - a knife with 2 legendary effects: beside the wounding effect, which causes targets to bleed for an additional 25 points of damage, it also gives an additional sneak attack damage multiplier of 0.5. You'll get it as a reward in the Pickmans Gift sidequest.

• Flakker - a Grenade Launcher with the legendary kneecapper effect, with a 20% chance to cripple the targets legs. You can find it by doing the When Pigs Fly sidequest. Sadly you can't get the nuke ammo grenades for this weapon, but on a weapons workbench you can change the receiver to fire 40mm frag grenades, which you can buy at some vendors.
  

• Kremvh's Tooth - a legendary weapon with a large damage boost, additional poison and bleeding damage. So run to Dunwich Borers, a big marbel quarry, west of the museum of witchcraft. Go all the way down and enter the Dunwich Borers through a door. Now follow the path till you reach a water hole. Dive in the hole and find next to some mini nukes the Machete.

• And don't forget to pick up the Cryolator after leveling up your skills. Actually you should have seen it in the beginning of game in Vault 111 in a locked case. But the case had a master lock and was unreachable for you at this time. So maybe the time has come now to head back and get a weapon that can freeze your enemies.
  

Actually there are four unique/rare "must have" weapons in the game. Sadly they has no legendary perks, so they are more or less powerfull. But it makes always fun to use them. At least with the sound they are producing while being equipt.

• Railway Rifle - shooting people with railway nails? Then this is your weapon. Reaching at least lvl 20 you can find it easily at the Bedford Station (east from the Museum of Freedom) - inside a blue railway car attached to a locomotive.
  

• Junk Jet - shoot with all what you put in it, even a coffee cup, a dinnertray or a typewriter. A similar weapon appears in Episode 1 of the Fallout TV series, in which it is used to launch the leg of a doll to kill a guard. You can find the weapon on a table inside the ArcJet Systems building, in the west of Graygarden.
  

• Saw Blade Launcher - Sold by Suggs next to the street between Campus Low Offices and Cambridge Crater. Needs saw blades as ammo.
  

• Baseball Launcher - You can find it by doing the sidequest When Pigs Fly. Needs explosive baseballs as ammo.
  

Maybe this guides are also interesting for you:
https://test-steamproxy.haloskins.io/sharedfiles/filedetails/?id=3323162276
https://test-steamproxy.haloskins.io/sharedfiles/filedetails/?id=3335971972
For more Fallout 4 Guides just have a look at my Profile

Special thanks to kaishark for his support.

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