Llanberis is a great spot in the heart of the peaks. My top tip is the National Slate Museum. It is a prime choice for a free day out. You can see how men worked the stone long ago. The town sits on the edge of Llyn Padarn. It is a deep, blue lake. You can walk the path to see the Lone Tree on the shore. From the town, you see the high peak of Yr Wyddfa. For a low cost trip, walk to the stone tower of Dolbadarn Castle. It stands on a rocky hill. A small train goes to the top of the peak. Life here is busy with walkers. It has deep roots in the slate trade.