Here is the India Gate, Qutb Minar, Red Fort, Humayun’s Tomb, Gurudwara Bangla Sahib, Akshardham some of the Visiting locations in Delhi, Capital of India

library(knitr)
## Warning: package 'knitr' was built under R version 3.5.3
library(leaflet)
## Warning: package 'leaflet' was built under R version 3.5.3
library(dplyr)
## Warning: package 'dplyr' was built under R version 3.5.3
## 
## Attaching package: 'dplyr'
## The following objects are masked from 'package:stats':
## 
##     filter, lag
## The following objects are masked from 'package:base':
## 
##     intersect, setdiff, setequal, union
m <- leaflet() %>%
  addTiles() %>%  # Add default OpenStreetMap map tiles
  addMarkers(lat=28.6129, lng=77.2295, popup="India Gate, Delhi") %>%
  addMarkers(lat=28.5244,lng=77.1855, popup="Qutb Minar, Delhi") %>%
  addMarkers(lat=28.6562,lng=77.2410, popup="Red Fort, Delhi") %>%
  addMarkers(lat=28.5933,lng=77.2507, popup="Humayun's Tomb, Delhi") %>%
  addMarkers(lat=28.6264,lng=77.2089, popup="Gurudwara Bangla Sahib, Delhi") %>%
  addMarkers(lat=28.6127,lng=77.2773, popup="Akshardham, Delhi") #%>%
  #setView (lat=28.6129, lng=77.2295, zoom=16) 
  
m  # Print the map

Mapping Clusters When you zoom in to each cluster, the cluster will seperate until you see the individual Markers!!

df <- data.frame(lat=runif(500, min=28.65, max = 28.75 ),
                 lng=runif(500, min=77.05, max = 77.15 ))    
df %>%
leaflet() %>%
addTiles() %>%  
addMarkers(clusterOptions = markerClusterOptions())