Welcome to Rivera!
Rivera is a city in the northern interior of Uruguay. It's the capital of the Rivera Department, located on the border with Brazil, right across from the Brazilian city of Santana do Livramento. Full of large hills and cheap shopping, Rivera's main attraction is its location on the border. Uruguayans come for the inexpensive goods on the Brazilian side, and Brazilians come for the duty-free shops on the Uruguayan side. Travelers from other countries can take advantage of both. Rivera also gives you the chance to stand a foot in each country, a cool photo opportunity.
To a large extent, Rivera and Santana function as one city: you can easily take a day trip from one to the other without even bringing your passport. You may not even notice you're crossing the border, which is marked by inconspicuous white border markers. If you decide to venture further into the other country, though, make sure to stop at immigration (located next to Siñeriz Shopping) to get your passport stamped out of one country and into the other.
That being said, they are two different cities, with separate bus systems and administration and somewhat different vibes. Being in Uruguay, Rivera tends to be a bit more expensive than Santana, serves more Uruguayan foods like chivitos and milanesas, and has more Spanish than Portuguese. On both sides of the border, though, it's not uncommon to have a conversation where one side is speaking Spanish and the other Portuguese, or where both sides are speaking Portuñol, a mixture of the two languages.
Rivera is the capital of the Rivera Department of Uruguay. The border with Brazil joins it with the Brazilian city of Santana do Livramento, which is only a street away from it, at the north end of Route 5. Together, they form an urban area of around 200,000 inhabitants. As of the census of 2011, it is the sixth most populated city in Uruguay.