Fantastic hiking spot. It offers everything you need. Great views, a lot of rocks, steep and well maintained trails. It can be crowded on a nice day. I highly recommend good hiking shoes which protect your ankle. You basically have to walk on rocks most of the time. Definitely worth a trip from Boston.
The most frequently climbed mountain in the US
Here is some additional information in pulled from Wikipedia:
Mount Monadnock is a mountain in the New England state of New Hampshire. It is the most prominent mountain peak in southern New Hampshire and is the highest point in Cheshire County, New Hampshire. It has long been known as one of the most frequently climbed mountains in the world. At 3,165 feet (965 m), Mount Monadnock is nearly 1,000 feet (300 m) higher than any other mountain peak within 30 miles (48 km) and rises 2,000 feet (610 m) above the surrounding landscape. Mount Monadnock, 62 miles (100 km) northwest of Boston and 38 miles (61 km) southwest of Concord, is located within the towns of Jaffrey and Dublin, New Hampshire.
The term "monadnock" has come to be used by American geologists to describe any isolated mountain formed from the exposure of a harder rock as a result of the erosion of a softer rock that once surrounded it (a landform termed inselberg elsewhere in the world).
Monadnock's bare, isolated, and rocky summit provides expansive views. A number of hiking trails ascend the mountain, including the 110-mile (180 km) Metacomet-Monadnock Trail and the 50-mile (80 km) Monadnock-Sunapee Greenway.[4]
It remains clear largely because of fires set by early settlers.