Downtown Houston is the heart of the nation's fourth-largest city, a cluster of glass skyscrapers connected by a seven-mile underground tunnel system that lets you walk between buildings in air-conditioned comfort during the brutal summer heat. The tunnels are a world unto themselves, lined with restaurants, shops, and coffee stands, and they are packed with office workers at lunch.
The Theater District, concentrated around Smith and Texas streets, is one of the largest performing arts centers in the country. The Houston Symphony, Houston Ballet, Houston Grand Opera, and the Alley Theatre all have their homes here, and you can often find same-day tickets at reasonable prices. Bayou Place, a converted convention center, anchors the entertainment scene with restaurants and live music venues. Nearby, Market Square Park and the surrounding blocks have become a dining and nightlife destination, with restaurants like Niko Niko's and Hearsay serving the after-work crowd.
Sam Houston Park, tucked between the skyscrapers, preserves a collection of historic homes dating from the 1820s through the early 1900s, offering a jarring contrast to the modern towers around it. The Heritage Society Museum in the park tells the story of Houston's transformation from a muddy frontier town to an energy capital. On weekday evenings and weekends, downtown empties out considerably, so time your visit for when the theaters and restaurants are in full swing.