Silence and two freiends

Lead is one of the more difficult words in English because it has so many different meanings and different pronunciations.

1/ In the sense of "condurre", "lead" (pronounced "leed") is used in the present tense. "Led" (pronounced with a short "e", the same way as the metal piombo is pronounced in English) is the passato prossimo form which applies here.

2/ You wouldn't say "till" (which is an informal form of "until" in this context) in this way. You might say "Follow this road until you see the Autostrada", or "until we arrived there", but not just "till / until there". (You might, however, say "till then", referring to a time rather than a place.)

3/ Also this would only be the case if she rode her Vespa and you followed her in another vehicle or on another motorcycle. If you rode on the back of her Vespa, you would say "took me there on her Vespa".

At that time I didn't really know her that well; we had one friend in common so I started to get to know her. I was in Florence to meet my friend, but she worked at night so Valeria (that girl with the Vespa) invited me to go out with her so here we are ... in a late summer night with a breathtaking view over the ancient city of Florence.

Although you can use the present tense to describe a past event in English, this was clearly quite a while ago. (You don't remember how long ago.) I would therefore use the past tense here; "there we were" instead of "here we are".