La Sirena is a huge supermarket/mall where you can buy anything: Grocery, clothes, sports articles, books etc.
You can also buy your souvenirs here and at a cheaper price than a tourist shop.
There are a couple of La Sirena’s in Santo Domingo, but I have only visited the one at Ave. Winston Churchill.
February is the month of our mother land (el mes de la patria) and this is particularly celebrated at all the Multicentro La Sirena shops by having a festival during all of February where they sell Dominican products at excellent prices. This year they have an artisan making products in clay in store.