James Glassman was looking for another project when he realized he’d been writing another book all along—140 characters at a time.

Since 2010, Glassman—an architecture project manager who runs the Houstorian website and wrote The Houstorian Dictionary: An Insider’s Index to Houston (2015)—has been sharing historic H-Town anniversaries from his Twitter account, @houstorian. The Houstorian Calendar: Today in Houston History pulls together notable city events, Houstonians’ birthdays, sports milestones, and other fascinating moments in time—one for each day of the year.

“I basically wrote this book on my iPhone,” Glassman laughs. This time, though, there's plenty of photos and no character limit.

The project was more difficult than it may appear. “You can’t just Google ‘give me every March 4 in Houston history,’ and expect to find anything,” he says. “It’s like collecting anything else. You have to be patient. It took several years, but I got every single day on the calendar.”

It was almost like a treasure hunt. Glassman would be reading an article, or see something on TV, and it would lead to one fact, then another, until he struck tweetable gold. For example: “Look, there’s a documentary on [Houston tennis player] Zina Garrison,” Glassman explains. “I wonder when she was at Wimbledon. Oh, look, I’ve found something.”

In the end, the hardest part about compiling the book was picking just one event per day to write about. June 1, for example, is not only the same day Jesse Jones and John de Menil died (in 1956 and 1973, respectively), it’s also the day the Shamrock Hotel was demolished (in 1987).

“Sometimes so many bad things happened in one day,” Glassman says. “I don’t believe in astrology or numerology, but it makes you think twice sometimes.”