The San Francisco 49ers announced their preseason schedule, which includes games against the Minnesota Vikings, Houston Texans, Denver Broncos and San Diego Chargers.The NFC West champion 49ers open at home against the Vikings, then travel to Houston to take on the Texans in Week 2. Dates and times for the first two games have yet to be determined.The highlight of the schedule comes on Aug. 26, when the 49ers hit the road to take on the Denver Broncos, led by new quarterback Peyton Manning in a nationally televised game. The Broncos hold a 18-15 advantage in 33 prior preseason contests against the 49ers.The Chargers come to Candlestick Point in Week 4 to wrap up the preseason schedule on Aug. 30. The Chargers and 49ers have met in the preseason for 26 consecutive years and the all-time series is tied with each team winning 20 games. However, the 49ers are 13-4 in preseason games against the Chargers at home.There is one notable absence from the 49ers' preseason schedule: a game against the Oakland Raiders. In last year's contest at Candlestick Park, two men were shot in separate incidents in the parking lot.