A hundred years ago, if you wanted to tell your friend what time you’d be catching the train from Union Station, you couldn’t send a text or shoot off a quick email. Instead, you’d write a postcard, and mail it for a cent.

“Greetings from Washington,” a new exhibit at the small but elegant George Washington University Museum in Foggy Bottom, tells the history of the District through postcards. Over 100 cards are grouped according to their time period and style, from brightly painted cards from the “Golden Age” of postcards in the early 1900s, to photochrome cards that businesses distributed in the 1980s and 1990s as an easy form of advertising.

One of the exhibit’s most charming sections is its series of “HTL,” or “hold to light” postcards. All featuring landmark D.C. buildings, the cards have tiny holes where the buildings’ windows would be. When a visitor flips a switch, a backlight illuminates the windows, creating a Thomas Kinkade-like effect.