The drive from Lisbon up to the little walled town of Óbidos is a lovely one, winding through the hills, rushing past other towns along the way. Óbidos is a wonderful half-day trip from Lisbon where visitors can walk the entire perimeter of the town from high above on the castle walls, wander the idyllic streets and enjoy a slower pace for a while.
I wouldn't suggest a full-day trip here as it's a small place, but well worth a few hours of exploring. A direct bus line runs here from Lisbon, the Rapida Verde, which you can board at Campo Grande train station. Tickets are 8 euros per adult each way, with discounts for youth and seniors available. You pay in cash on board the bus each way. Check out the daily schedule here.
Here are the snaps I took of the delightful autumnal colours in full force in this quaint little town: