Finding 221b Elysion Boulevard in Lies of P can be a little tricky, but it's a key part of the Crafted Cryptic Vessel puzzle, which gives you a photograph of the house, but no indication of exactly where it is in the region. You'll have to use all your puzzle smarts to locate the address—or you can just find out lower down in this guide.
If you've yet to fully explore Krat, there are plenty of weapons scattered around its regions. If you have the Crafted Cryptic Vessel already, that means you can unlock boss weapons by finding Alidoro in the cathedral. Otherwise, here's the 221b Elysion Boulevard location and how to get the Crafted Cryptic Vessel that will lead you to its front door key.
Where to find the Crafted Cryptic Vessel
In order to open 221b Elysion Boulevard, you first have to locate the Crafted Cryptic Vessel item. You can find this in St. Frangelico's Cathedral. When entering the cathedral depths from the St. Frangelico's Cathedral Chapel Stargazer, you'll find a room flooded with black water, plus a ladder and some rafters that'll lead you up to its very top. Up here, you'll find a burning brazier you can push off the ledge to burn that black liquid away, revealing a staircase leading down into a hidden room, and a chest containing the Crafted Cryptic Vessel.
Take this to Venigni in Hotel Krat and he'll decipher it into a note instructing you to throw an object at the puppet hanging from Alchemist's Bridge on Elysion Boulevard. You'll remember this as the place where you fought the Mad Donkey boss. Simply target the puppet and throw an item—remember that you can purchase Sawtoothed Wheels from Polendina in Hotel Krat if you're out. Hitting the puppet will knock free a photograph of 221b Elysion Boulevard and a key to open the front door. First, though, you'll have to locate it.
Lies of P 221b Elysion Boulevard location
You can find 221b Elysion Boulevard close to the "Inside the House on Elysion Boulevard'' Stargazer. Just head out the door onto the balcony and then turn right and walk over the plank. The entrance to 221b is directly on your right, just before the pistol puppet looking out over the street. Unlock the door and enter to find a safe containing a Quartz for upgrading your P-Organs, and the Owl Doctor's Hunting Apparel costume.