Many of the grand buildings that inspire a travel sketch quite often are intimidating in the perspective challenges they present. Perspective seems daunting, I get that. Yet a few tips make it work.
Trust the process – horizon line and focal point, it all starts there. There are lines that just seem to be at extreme angles, yet if they converge on the focal point they will end up being right.
Start at the distant point or plane and work your way back to the foreground. This was a game changer for me, for I had this instinct to start close, yet always had it wrong when I got to the distant.
It really does help to use a straight edge to pencil in the converging lines, then go as loose as you want with the details.

This is the Biblioteca Mediciea Laurenziana in Florence, Italy. I will confess I was a bit daunted, but it was impressive and I wanted to revisit the day we were there in 2017, so I spent some time with an IPA at the hotel lounge, a photo, my Moleskein, and art-toolkit. The results works, and it was a good moment, both yesterday and in 2017.