If you want to know when GoogleBot visited your website recently you can use any of the following ways to do so
1. Go through your web logs which Apache/IIS generate for your website. Scan for GoogleBot. A very crude way indeed.
2. If you have signed up for Google Sitemaps then you can login into your account and find out when did GoogleBot visit your website. Not only that you also get up to date indexed pages of your website in Google as well as any crawl errors (if any).
3. If you don’t have time for the above two then just go to GBotVisit. Enter your website URL and copy the code it generates into the footer of your website (its up to you where you want to place it). Now, you know in real time when GoogleBot visits your website.
Hope the above helps