Which is the largest botanical garden in the world? Name a few well known Botanical gardens in India.

Explanation

### Step-by-Step Solution:

1. **Identify the Largest Botanical Garden in the World**:
- The largest botanical garden in the world is the **Royal Botanical Gardens**, which is located in **Kew, London**.

2. **List Well-Known Botanical Gardens in India**:
- One of the most famous botanical gardens in India is the **Indian Botanical Garden**, also known as **Botanical Garden of Kolkata**, situated in **Shibpur, Howrah, Kolkata**. It is the largest botanical garden in India.
- Another notable botanical garden is the **National Botanical Research Institute (NBRI)**, located in **Lucknow**.
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