Joshua - Chapter 6
"Joshua Fit the Battle of Jericho"
Joshua sealed the city of Jericho so that nobody could enter or leave. The army circled the city once a day for six days, following which seven Kohanim would blow shofar. On the seventh day, the army circled the city seven times. When the Kohanim blew shofar, the city walls collapsed. The city was routed but, as promised, Rachav and her family were spared. (As mentioned earlier, they converted and joined Israel.) Joshua placed a curse on anyone who would rebuild Jericho, or even call another city by that name. (This prohibition is not listed among those applicable to us in either the Shulchan Aruch or the Rambam, as it only applied to the initial rebuilding of Jericho, long since past. So if you live in Jericho, NY, don't worry about it.)
Unlike the lyrics of the once-popular song, the walls of Jericho did not "come tumbling down." Rather, they sank straight down into the ground. This creates a quandary, as we were already told that Rachav's house was built into the city wall. One answer is that only the portion of the city wall adjacent to the army sank. Another explanation is that Rachav's house probably wasn't built completely into a hole in the city wall. Rather, the city wall probably also served as one wall of the house. When the city wall sank, it would have left only that one side exposed.