That would be Matamoros, across the border from Brownsville, TX.
The confedarate national flag went through several phases. First was the "Stars and Bars." it was a red flage with a white stripe through the middle running horizontaly, and in the upper left corner, 11 stars on a blue field. That looked to much like the American flag, so they changed it to a white flag with a Confedarate Battle flag in the upper left corner. That looked to much like a surrender flag, so the final version was the sane, but with a vertical red sripe on the right side. The battle flag is a red square with a white "X" going from cornre to corner from both directions. Insode that was a smaller blue "X" containing 13 stars. One in the middle, and three on each leg ogf the "X." The Naval Jack was the same as the battle flag, but it was rectangular, like a normal flag. So the confederacy had 5 oficial flags overall.