Hear the stories behind Houston’s sky-scrapers on the Downtown’s Evolving Skyline Architecture Walk, including the scoop on the construction of the Gulf Building (now JPMorgan Chase & Co.). Jim Parsons, director of special projects for Preservation Houston, says it was in the late 1920s and the steel frame for the 14-floor structure was already in place when the engineer, Willard Simpson, got a call from his boss for the project, Jesse H. Jones. “[He] wanted to add four floors. That meant a lot of engineering work to strengthen the columns at the bottom of the building so they would support that extra height…Simpson said he would need time to do the calculations, and Jones said, ‘Okay, I’ll hold.’ Simpson didn’t want to disappoint Jesse Jones — no one did — so he figured it all out in a hurry, and the building was the tallest in the South when it opened thanks to that extra height.”

The tour follows the more or less chronological progression of Houston’s downtown skyline, from low-rise Victorian charmers built in the 1890s to the iconic skyscrapers of the 1980s. “During the 20th century, Houston went from being a small, human-scale, walkable town to an enormous, heroically scaled city, and you can see that in the design of the downtown buildings. I think it’s really interesting to get to see examples of all the different periods in skyscraper design, from the really ornate buildings at the turn of the century to the very sleek, contemporary towers we’re building today. Looking at them in roughly chronological order lets you get a sense of how styles and building technology evolved, and also how the scale of the city changed.”

5:30 p.m. Rice Lofts, 909 Texas. (Look for the guides at the northwest corner of Main and Texas.) For information, call 713‑510-3990 or visit preservationhouston.org. $10.

Sun., June 15, 5:30 p.m., 2014