Following last fall's news of cracked steel beams at the Transit Center and a cracked window at the sinking Millennium Tower, two cracked windows at Salesforce Tower have a lot of people very nervous.

The two windows, one on the 12th floor and one on the 14th floor of Salesforce Tower, were discovered this week, as NBC Bay Area reports. The 12th floor window cracked on Tuesday, and the 14th floor one happened Thursday.

Building owner Boston Properties issued a statement saying, "Because the cracks were on the interior panes of the double-paned windows, there was never any danger of glass falling to the street. We acted immediately to retain top glass safety consultants to help us determine the cause of these isolated failures and to take all necessary preventative steps."

As the Chronicle reports, the Department of Building Inspection "was made aware of [the cracked windows] after an inquiry from the Chronicle."

An inspection into the cause of the interior-pane cracks is ongoing, but the situation is unnerving given that these three buildings — Salesforce Tower, the Transit Center, and Millennium Tower — are all neighbors on a piece of land where we all know — via the Millennium Tower story that broke in August 2016 — it's just Bay mud underneath. And while the designers of Salesforce Tower famously drilled down to bedrock for its foundation, Millennium Tower's did not, and the developers of the latter building have put the blame on the Transit Center construction for causing their tower to sink.

Per the Chronicle, Millennium has sunk 18 inches since it was constructed in 2009, and it's still tilting slightly to one side — a problem that is going to be extremely expensive to fix. But the scare last September about a cracked window in the building was resolved when inspectors determined that it had been caused by some unknown external impact.

As for the Transit Center troubles, that seems to be less about the ground underneath than something about the steel itself and the weight of the rooftop park, but that has also yet to be officially determined.

Photo: Dawn Endico