Mt. Lincoln stands over 5000 feet tall along the Franconia Ridge in New Hampshire. To the north on this ridge is Mt. Lafayette and to the south of Lincoln are Little Haystack, Liberty and Flume. It's a popular summit and is usually done as part of the Franconia Ridge Traverse along with Lafayette and Little Haystack.
It can be accessed from the north or south on the Franconia Ridge Traverse and is .96 miles south of Lafayette on the ridge as well as 1.67 miles north of Little Haystack. The views are incredible including Washington to the north.
Here is a useful link with additional information as well.
Also, White Mountains Info Server
From Boston, take Interstate 93 north into New Hampshire. Take the exit just north of Woodstock, NH that says Mt. Lafayette Campground. The trailheads for either direction both start from this parking lot.