The Newton Crowne Plaza Hotel straddles the Mass Pike at Newton Corner. Here, the area south of the Pike is within the eruv, but the area north of the Pike is not. Just a few blocks west of here, the eruv includes both sides of the Pike, and there are four places you can cross the Pike while carrying. Here are the details:
When you are carrying on Shabbat, two Tzurot Ha-Pesah allow you to enter and exit the hotel from only the south side of the hotel (and not through the automatic electric doors at the main lobby entrance). Stay on the south side of the red line in the photo above.
In the map below, the red route lies entirely within the eruv. This route is one-and-a-quarter miles long, and includes a hill. The green route lies partially outside the eruv. This route is three-fourths of a mile long, and level. Click the map to see it full-size. Also, read the detailed instructions below.