To find and engage in Twitter conversations happening in specific geographical areas that are relevant to your company, you should use:

Geo-search streams in Hootsuite allow you to monitor Twitter conversations within a defined geographical area, making them ideal for finding and engaging with local discussions relevant to your company. Hootsuite campaigns are for managing marketing initiatives, not for real-time local conversation monitoring. Geo-targeted messages are for sending content to specific locations, not for finding existing conversations. Location tags are used when posting content to indicate a location, but don't create a stream for monitoring. Internal/external tagging is for organizing content within Hootsuite. The Hootsuite Surveillance feature does not exist.