First settled in 1630, Watertown has somehow managed to go through almost four centuries of eventful history without ever acquiring any particularly distinctive identity. One might expect that, lacking any other identity, Watertown would identify as a suburb of Boston, but this would be a mistake. Most residents of Watertown seem to be oblivious to the fact that they live about six miles away from Beacon Hill.
This is not to say that Watertown has no civic spirit. Locals share a dislike for neighboring Belmont, a loyalty (not entirely deserved) to eating establishments such as Stellina's and Tresca's in Watertown Square, a willingness to pretend that such annual events as the Faire on the Square are more fun than they actually are, and a sense of general satisfaction when one of the high school sports teams wins something. (Even if, as is often the case, they don't know the name of a single player.) Furthermore, Watertown's relative lack of identity may not be an entirely bad quality, when one considers the rather unillustrious identity of its neighbors.
(Cambridge = Harvard University and assorted fiefs; Somerville = Cambridge's ugly cousin; Belmont = home to a prep school and the gated-community-with-everything-except-an-actual-gate of Belmont Hill; Brookline and Newton = a subdistrict of the state of Israel, confusingly located in eastern New England.) (An exception is Waltham, which is quite nice.)
Watertown's architecture is low-key chaos. It's not unusual to find an 18th century colonial farmhouse, a small Victorian mansion, a few triple deckers, some colonial revivals from the early 20th century, and some unclassifiable mish mashes from the late 20th century all sharing the same block. Beside that, you have the usual New England mix of white wood-and-brick Protestant churches and gargantuan stone Catholic churches, and the beautiful 19th century brick buildings that used to be mills and are now either office space or condos. (At least one church has also been converted into condos.)
Formerly a manufacturing town, Watertown has been undergoing a process of de-industrialization and gentrification for at least two decades. The town's factories and warehouses have been dismantled (or, along the Pleasant St. corridor in the southwest part of town, simply left to rot, though the town council is making noises about revitalizing the area), and the buildings of the former arsenal have been converted into offices, restaurants, recreational facilities, and a thus-far-not-particularly-interesting arts center. Property has become more expensive. (Though less so than in most of the surrounding area, partly due to the fact that Watertown has sources of revenue other than property taxes. The town has three commercial districts: The town center, the Coolidge Square area to the east, and a mall complex to the southeast, along the Charles River, which is more or less the southern boundary of the town.)
In one respect, this trend is welcome, since frankly nobody misses the sullen plebes who constituted Watertown's now-priced-out middle class. In another respect, the trend is worrisome, since Watertown seems to be slowly becoming a community consisting of rich people, poor people, and nothing in between. (Watertown's poor mostly consist of Middle Easterners and Latin Americans living in the vicinity of Coolidge Square.) (The trend toward "rich, poor, and nothing else" has, of course, also been underway in the United States in general for the last several decades.)
This definition reads more negatively than I intended, so I will close by mentioning some things about which Watertown can legitimately brag: Mount Auburn Cemetery (which has a Cambridge address, but is almost entirely encompassed by Watertown); a good (recently overhauled) public library; beautiful places to walk along the Charles River (also recently overhauled); the Perkins School for the Blind (perhaps better known to the nation as "the place where Helen Keller did things").
Urban Dictionary Contributer: "GOD NO THERE'S NOTHING TO... wait, which one?"
Random Guy: The one in (insert "Massachusetts", "Connecticut", or "South Dakota" here at your discretion).
Urban Dictionary Contributer: "GOD NO THERE'S NOTHING TO DO THERE!"