Try some of these places...
http://www.ci.austin.tx.us/ansc/
http://www.blantonmuseum.org/
http://www.ci.austin.tx.us/zilker/gardencenter.htm
http://www.wildbasin.org/
http://www.ci.austin.tx.us/zilker/
http://www.tspb.state.tx.us/SPB/Plan/Tours.htm
http://www.austinexplorer.com/hiking/HikeDetail.asp?HikeID=481
http://www.austin360.com/search/content/events/special/bats.html
http://www.lbjlib.utexas.edu/
http://www.texasoutside.com/townlakemap.htm
http://austin.about.com/od/austinattractions/tp/downtown_tops.htm