Houston Tunnel System

The Houston tunnel system is the world's largest indoor air-conditioned pedestrian
tunnel system. It includes 7 miles of underground pedestrian tunnels and
skywalks connecting 65 buildings in downtown Houston, Texas.
Address: Houston Tunnel System, Visitors
Information Center, 901 Bagby Street, Houston, Texas 77002-2526; 713-222-9255.
Web: http://www.houstondowntown.com/
home/default.asp.
Lyndon B. Johnson
Space Center

This is the headquarters, also known as Mission Control, for the United
States's manned space program. The visitor center features live shows,
interactive exhibits, an IMAX theater, behind-the-scenes tours, live satellite
links, and more.
Address: Lyndon B. Johnson Space Center,
National Aeronautics & Space Administration, 2101 Nasa Road 1, Houston, Texas
77058-3607; 281-244-2105. Web: http://www.nasa.gov/
centers/johnson/home/index.html.