We are going configure Agenda Module to display Google Calendar Events to Drupal site. It read both Private and Public calendar and you can use one or more Google Calendar in a single Block. And it also provide some disign for your Agenda Block , but if you want to change, you can easily do with simple css.

Step 1: Enable Agenda Module

As similiar to other module, just download Agenda Moduleand extract it to sites/all/modules and finally enable from admin/modules.

Step 2:Configure Agenda Module

once you enable this module, then its time to configure it with your Google Calendar(public/private). In your Drupal site open admin/config/services/agenda where you will find " Example agenda block" which is for example purpose, So need to worry about that. From there "Add New Block".

1. Give Administrative title
2. Agenda Start and End
3. Maximum number of Events to fetch
4. Date and Time Formate
5. Field To Display and label to hide
6. Google Calendar ID
7. Google Calendar API

How to to get Google Calendar IDand Google API Key

Save these setting.

Step 3: Block Assign to Region

After you configured Agenda setting its time to show Google Calendar Events to the regions in your Drupal Site. So , go to admin/structure/block , there you find a block with name "Agenda:Administrative title"(i.e the title you given during configuration in step 2 for "Administrative title"). Configure this block to region. You will get your Google Calendar Events listing there.