Walking along Lisbon's tree-and-poo-lined streets, in deliciously sweltering days that make you sweat when you think, with warm nights, stunning sights, carnivourous meals, sangria and incredibly hospitable hosts... I am reminded again why I travel.

And in my first experience as a Couchsurfer - I have hosted a few times, never before guested - I can certainly recommend it. For those who aren't familiar, is an international site where users can either stay or host for free in their own homes. Of course, a bottle of wine or a dinner or a gift is a basic courtesy to extend to the host.

The daunting idea of having a complete stranger in your home (or you in theirs) is made much less daunting by having users complete extensive profiles of themselves, along with references from people they've met via their travels.

You can also filter your preferences when searching for a place to stay (i.e. age range, gender, etc) and make explicit guidelines for people looking to surf at your place (i.e. no smokers, female/male only, no Republicans, etc.). It's also a great way to see a city outside of the normal tourist-greased conveyor belts.

And so it is that I have to mention Rita and Raquel, two Portuguese sisters who are my first ever hosts (and I am their first guest).

I normally have a strict rule to not mention details of my personal encounters on this blog, but these girls deserve special mention. I didn't know people like this still existed. Sweet, polite, charming, fun, incredibly helpful... If all couchsurfing experiences are like this, hotels will go out of business.

They have quickly helped make Lisbon one of my favourite cities. More as the week progresses...