When the Mexican government asked Swiss surveyor Jean Jacques Vioget to map out a plan for the burgeoning village of Yerba Buena in 1839, he opted for the standard European model of a grid of streets and a central plaza that would overlook the cove a block away. It was the birth of modern-day San Francisco, and in the 170 years since then, the plaza has seen more action than any other spot in the city. A month after the 1846 Bear Flag revolt in Sonoma, 70 soldiers and marines from the U.S.S. Portsmouth entered the plaza and raised the American flag. A year later, the first public school in California was established in the newly named Portsmouth Square, and the year after that, newspaperman Sam Brannan strode about the premises announcing to the city and the world that gold had been discovered in the Sierra foothills. In 1849, the Wigwam restaurant opened for business in the square (it's known today as the Tadich Grill); the Committee of Vigilance hosted occasional necktie parties through the 1850s; the world's first cable car chugged up Nob Hill from its starting point at Clay and Kearny in 1873; Robert Louis Stevenson was a regular in 1879 and 1880 (there's a brass and granite monument to him nearby); and hundreds camped out in the plaza after the 1906 earthquake and fire.