Aosta is a place we go to occaisionally from Chamonix - don't look here for tips on hotels as we have never stayed overnight!
We go to Aosta as a day trip from Chamonix France, via the Mt Blanc tunnel.
Aosta has great food, Roman ruins, a beautiful old section of town and some really nice shopping areas.
The drive from the Mt Blanc tunnel to Aosta is very beautiful. I recommend that you do NOT take the motorway if you are just going to Aosta. The motorway goes through tunnels the entire way and you will never see the beautiful valley - take the smaller road instead. There are several cities along the way which have old castles you can visit, or ruins of monestaries, chateaus etc..