I'm upgrading my Legendary Fort to level 2 but now can't access the fort to see the pirates within. There's no icon above it and the only options when clicking it are Details, Rotate, Cancel, Complete.
By my recollection, many buildings don't function until upgrade is finished. Tavern might be the only one that DOES. You can micro-pay, er, gem it if you want it now.
You still can view inside it if your current pirate is active, and your base gets attacked. You get a pop up message that lets you go to the fort (presumably to put him in rest mode) and within there you can change outfits and upgrade him despite it currently being upgrading. I mentioned this in another bug thread, and heard that its actually intended that you be able to view the fort while upgrading (again, this is required to switch active pirate, nevermind training) Unfortunately I doubt this will be fixed before you make it to lv3 fort :c but after that you'll never have to worry about it again! edit: also, if you just want to check the ship to hire a pirate, or purchase an outfit (which you still have to sneak into the fort in the aforementioned way to equip), there's a button in the upper right that brings you to the ship!
As Skye mentioned, if you are "lucky" enough to be raided, you will get a popup saying that your Legendary has lost stamina when you were raided. That popup has a link to the Fort, where you can upgrade your legendary even while the fort is upgrading. Level 2 upgrade is 1 hour and not very expensive, but you will need materials. For my Romeo Boomer, it was 3 Gunpowder, 120,000 Grog and 250 BP.
Yep, I got attacked and managed to get into the fort from the pop-up about the pirate stamina. I also managed to upgrade him from there even though the fort is upgrading!
one more note, if you are upgrading your fort and manage to sneak in to upgrade your Legend, he is no longer avaialable for attacking or defending. Apparently you have to 'activate' him again after each training, so now he is level 2 but I cannot get into the fort to activate him until the fort finishes upgrading...