Seeing the interview MNTC had with the Executive Director of the Woodman Museum in Dover, NH got me thinking about all of the possible TMNT locations and landmarks if one wanted to make a TMNT pilgrimage.
The Hotel Northampton

Address: 36 King St, Northampton, MA 01060
Significance: Where the final version of the Creator's Bill of Rights was signed. Many independent comic book legends got together here to make a statement to the comic book world about the importance of creator rights. Also appeared in issue #14.
Original Mirage Studios

Address: 28 Union St. Dover, NH 03820
Significance: There was no "studio" here. It was a "mirage." There once stood a house in this lot in Dover, NH where Eastman and Laird lived and first conceived the TMNT.
Northampton Mirage Studios

Address: 16 Market Street, Northampton, MA 01060
Significance: This is where the magic happened.
Hampshire County Superior Court

Address: 15 Gothic St, Northampton, MA 01060
Significance: To commemorate Northampton's 350th Anniversary in 2003 and to raise money for Northampton schools, Kevin Eastman and Simon Bisley created a painting of a ninja turtle sitting atop a bust of President Calvin Coolidge at the Hampshire County Superior Court.
Nicely's Market

Address: [CLOSED] 397 Ossipee Trl E, Gorham, ME 04038
Significance: The inspiration for the bull that sat atop Louie's in issue #14.
Bluebonnet Diner

Address: 324 King St, Northampton, MA 01060
Significance: The dinner where April worked in issue #14.
The Lucas Farm

Address: 27770 State Hwy 210, Currie, NC 28435
Significance: April O'Neil's farm in the 1990 movie based on the Jones Farm in the Mirage TMNT continuity.
Calvin Theatre

Address: 19 King St, Northampton, MA 01060
Significance: Seen next to Steve's Comics in issue #15. However, I can't find any information on whether or not a comic shop was ever there.