It's only the third week of classes and you may already be sick of the Common. If you're tired of always jogging the same paths and dealing with the weekend tourist crowds, there are other places you can go when nature calls and you need a change of scenery.

The Boston Common, built in 1634, is the oldest public park in the country. Yet, many do not know that the Common is actually part of a larger network of parks and green spaces known as the Emerald Necklace.

The Emerald Necklace was designed in the late 1800s by Frederick Law Olmsted, a landscape architect who also created Central Park in New York.

The six parks built by Olmsted are the Back Bay Fens, the Riverway, Olmsted Park, Jamaica Pond, the Arnold Arboretum and Franklin Park. The city of Boston eventually decided to include the Commonwealth Avenue Mall, Public Garden and Boston Common in the Emerald Necklace.

Each section of the Necklace is worth exploring, but to get the most out of one trip on the T, take the Orange Line to Forest Hills and check out the Arnold Arboretum and Franklin Park in Jamaica Plain.

Operated by Harvard University, the Arboretum is essentially a tree museum. It houses over 4,000 different varieties of woody plants. Cars aren't allowed inside the Arboretum, which makes winding roads and paths perfect for hiking, biking and rollerblading. Because the foliage is constantly growing and changing, any season is a good time to visit, but be sure to go at least once in mid-October when the leaves turn a rainbow of colors. The Arboretum is open from dawn to dusk 365 days a year and is open to the public free of charge (for more information, visit www.arboretum.harvard.edu).

While you're at Forest Hills, hop on the #16 bus to visit Franklin Park, which is the largest "gem" on the Emerald Necklace. Named for Benjamin Franklin, the 527-acre park is home to the nation's second oldest public golf course, the Franklin Park Zoo and 15 miles of pedestrian pathways, according to the Emerald Necklace Conservancy. While the zoo's admission fee is $9.50 and the golf course's fees vary, admission to the park grounds is always free to the public.

The Emerald Necklace isn't the only place to find a little green around the city. Many Emerson students know about the Boston Common, but did you know that there is another Common across the river?

Cambridge Common, just a short stroll from Harvard Square, is smaller than its Boston counterpart but it's also a lot less crowded. While in the area, you can't "pahk your cah in Hahvud Yahd," but you can bring a book and park yourself there on the grass of the Yard, which is Harvard's central lawn. There you can enjoy the blissful quiet it offers right beside the bustle of Harvard Square, and you don't have to be a Harvard student to do it.

Closer to Emerson's campus, there's a small but scenic spot in Post Office Square. From Downtown Crossing, walk down Franklin Street until you find the Norman B. Leventhal Park in the heart of Boston's Financial District. The Post Office Square slogan is "park above, park below" because Leventhal Park is built on top of a large parking garage. There's a fountain in the middle of the square that you can run through if it's particularly hot out, and the outdoor Milk Street Cafe is open year round. The area has plenty of inviting benches, but at lunchtime on a weekday you'll have to fight the square's many office dwellers for a seat.

If you're up for a real adventure, head out to Larz Anderson Park in Brookline. Take the MBTA Green Line/D Line to Reservoir and hop on the #51 bus. Ask the driver to stop at Newton Street and then follow the signs for the auto museum. The #51 bus doesn't run on Sundays, but there is plenty of free parking available if you can find a friend with a car.

It's worth all the effort, because Larz Anderson Park has almost everything you could want. There are baseball and soccer fields, gardens, a playground and a lagoon. At the head of the lagoon, a gazebo known as the "Temple of Love" is often used for weddings and special events. Small charcoal grills are also available for rent at the many picnic tables around the park. Hike up the hill to visit the Larz Anderson Auto Museum, America's oldest car collection, and while you're up there take in the spectacular view of the Boston skyline. Near the museum there is also a large ice skating rink, open from December to February.

Mark your calendars now for Brookline's 300th birthday celebration taking place at Larz Anderson Park on Nov. 13. There will be food, live entertainment and the first fireworks display in Brookline in over 60 years (for more information, visit www.brookline300.org).

So grab your T pass and a little bit of extra change and go explore. There's a big green world beyond Boylston Street if you just know where to look.