I've made an attempt at mapping Twain's route through Italy in the 
Spring of 1892.  This follows departing the French Riviera at Menton; to 
Pisa, Rome, Florence, Venice, and finally at Cadenabbia on Lake Como.  I 
have little to no detailed information on the specifics of the routes 
taken and have relied on an 1896 map of European railways - along with 
Google Earth's railroads overlay.

https://twainsgeography.com/content/italy-spring-1892

My map of routes is interactive, meaning it can be viewed in full screen 
and enlarged to a precise level.  If anyone has specific knowledge of 
exactly where they were in this time-frame it would be helpful, allowing 
me to fine tune the map.  I assume this would mean anyone with access to 
letters posted by Twain's daughters and/or Livy.  I'm thinking of the 
invaluable assistance provided by Miki Pfeffer and the note on St 
Gothard/Gotthard Pass.

Thanks...